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Securities (Details) (USD $)
3 Months Ended 6 Months Ended 12 Months Ended
Jun. 30, 2011
Jun. 30, 2010
Jun. 30, 2011
Jun. 30, 2010
Dec. 31, 2010
Trading Securities [Abstract]          
Fair Value, trading securities $ 99,846,000 $ 62,159,000 $ 99,846,000 $ 62,159,000 $ 55,467,000
Amortized Cost 349,583,000 353,277,000 349,583,000 353,277,000 339,553,000
Investments securities, fair value 369,247,000 363,886,000 369,247,000 363,886,000 346,105,000
Not Recognized in OCI Gross Unrealized Gain 19,668,000 [1] 10,885,000 [1] 19,668,000 [1] 10,885,000 [1] 8,417,000 [1]
Not Recognized in OCI Gross Unrealized Loss (4,000) [1] (276,000) [1] (4,000) [1] (276,000) [1] (1,865,000) [1]
Held-to-Maturity,Amortized Cost [Abstract]          
Held-to-Maturity,Amortized Cost,Less Than One Year 57,328,000   57,328,000    
Held-to-Maturity,Amortized Cost,One to Five Years 110,961,000   110,961,000    
Held-to-Maturity,Amortized Cost,Six to Ten Years 59,290,000   59,290,000    
Held-to-Maturity,Amortized Cost,Over Ten Year 122,004,000   122,004,000    
Held-to-Maturity,Amortized Cost,Total 349,583,000 353,277,000 349,583,000 353,277,000 339,553,000
Held-to-Maturity,Amortized Cost,Weighted Average Maturity (in years) 6.97 [2]   6.97 [2]    
Held-to-Maturity,Fair Value [Abstract]          
Held-to-Maturity,Fair Value,Less Than One Year 57,701,000   57,701,000    
Held-to-Maturity,Fair Value,One to Five Years 114,702,000   114,702,000    
Held-to-Maturity,Fair Value,Six to Ten Years 61,833,000   61,833,000    
Held-to-Maturity,Fair Value,Over Ten Year 135,011,000   135,011,000    
Held-to-Maturity,Fair Value,Total 369,247,000 363,886,000 369,247,000 363,886,000 346,105,000
Held-to-Maturity,Nominal Yield (in hundredths) [Abstract]          
Held-to-Maturity,Less Than One Year,Nominal Yield (in hundredths)     4.62    
Held-to-Maturity,One to Five Years,Nominal Yield (in hundredths)     4.87    
Held-to-Maturity,Six to Ten Years,Nominal Yield (in hundredths)     5.58    
Held-to-Maturity,Over Ten Year,Nominal Yield (in hundredths)     6.20    
Held-to-Maturity,Nominal Yield (in hundredths)     5.41    
Available-for-Sale Securities, Fair Value [Abstract]          
Available-for-Sale Securities, Fair Value 9,567,008,000 9,105,828,000 9,567,008,000 9,105,828,000 9,235,621,000
Available-for-Sale Securities, Debt Maturities, Fair Value [Abstract]          
Available-for-Sale Securities 9,567,008,000 9,105,828,000 9,567,008,000 9,105,828,000 9,235,621,000
Available-for-Sale Securities, Gross Realized Gain (Loss) Disclosures [Abstract]          
Related federal and state income tax expense     3,973,000 4,833,000  
Available-for-Sale Securities, Portfolio Concentration Ratings, Fair Value [Abstract]          
Available-for-Sale Securities, Fair Value 9,567,008,000 9,105,828,000 9,567,008,000 9,105,828,000 9,235,621,000
Distribution of Amortized Cost and Fair Value For Below Investment Grade Residential Mortgage-Backed Securities [Abstract]          
Number of Securities 60   60    
Amortized Cost 469,396,000   469,396,000    
Fair Value 407,321,000   407,321,000    
Credit losses Recognized [Abstract]          
Number of Securites in Current Period 34        
Amount of Credit Losses Recognized in Currrent Period 4,303,000        
Number of Securites in Life-to-Date 44   44    
Amount of Credit Losses Recognized in Life-to-Date 60,507,000        
Other-than Temporary Impairment Credit Losses Recognized in Earnings [Roll Forward]          
Balance of credit-related OTTI recognized on available for sale debt securities at beginning of period 57,223,000 29,367,000 52,624,000 25,142,000 25,142,000
Additions for credit-related OTTI not previously recognized 37,000 791,000 37,000 1,789,000  
Additions for increases in credit-related OTTI previously recognized when there is no intent to sell and no requirement to sell before recovery of amortized cost 4,787,000 1,855,000 9,386,000 5,082,000  
Balance of credit-related OTTI recognized on available for sale debt securities, end of period 62,047,000 32,013,000 62,047,000 32,013,000 52,624,000
Taxable equivalent basis - effective tax rate (in hundredths)     39.00%    
Average expected Life of Mortgage Backed Security (in years) 2.92   2.92    
Securities Pledged as Collateral For Repurchase, Amortized Cost 3,600,000,000 4,800,000,000 3,600,000,000 4,800,000,000 5,300,000,000
Aggregate Unrealized Loss on Private Issue RMBS 62,000,000   62,000,000    
Estimated Unemployment Rate , Maximum (in hundredths) 9.50%   9.50%    
Estimated Unemployment Rate, Minimum (in hundredths) 8.00%   8.00%    
Estimated Liquidation Costs For Jumbo Loans , Minimum (in hundredths) 25.00%   25.00%    
Estimated Liquidation Costs For Jumbo Loans , Maximum (in hundredths) 30.00%   30.00%    
Estimated Liquidation Costs For Alt A Loans , Minimum (in hundredths) 35.00%   35.00%    
Estimated Liquidation Costs For Alt A Loans , Maximum (in hundredths) 38.00%   38.00%    
Discount Rate Used To Estimate Cash Flow, Minimum (in hundredths) 2.90%   2.90%    
Discount Rate Used To Estimate Cash Flow, Maximum (in hundredths) 6.25%   6.25%    
Mortgage Trading Securities Fair Value 553,231,000 534,641,000 553,231,000 534,641,000 428,021,000
Mortgage Trading Securities Unrealized Gain or Loss     5,700,000 14,000,000 5,600,000
Mortgage Trading Securities Realized Gain or Loss 6,400,000 14,600,000 9,900,000 15,100,000  
Trading Securities [Member]
         
Trading Securities [Abstract]          
Fair Value, trading securities 99,846,000 62,159,000 99,846,000 62,159,000 55,467,000
Net Unrealized Gain (Loss)     (290,000) 131,000 59,000
Trading Securities [Member] | Municipal And Other Tax Exempt Securities [Member]
         
Trading Securities [Abstract]          
Fair Value, trading securities 62,285,000 18,866,000 62,285,000 18,866,000 23,396,000
Net Unrealized Gain (Loss)     (249,000) (15,000) (214,000)
Trading Securities [Member] | Obligations of the U. S. Government [Member]
         
Trading Securities [Abstract]          
Fair Value, trading securities 11,825,000 12,786,000 11,825,000 12,786,000 3,873,000
Net Unrealized Gain (Loss)     (37,000) (8,000) (17,000)
Trading Securities [Member] | Other trading securities [Member]
         
Trading Securities [Abstract]          
Fair Value, trading securities 2,997,000 4,031,000 2,997,000 4,031,000 927,000
Net Unrealized Gain (Loss)     (13,000) 3,000 (2,000)
Trading Securities [Member] | US Government Agencies Debt Securities [Member]
         
Trading Securities [Abstract]          
Fair Value, trading securities 22,739,000 26,476,000 22,739,000 26,476,000 27,271,000
Net Unrealized Gain (Loss)     9,000 151,000 292,000
Available-for-sale Securities [Member]
         
Available-for-Sale Securities, Amortized cost Basis [Abstract]          
Available-for-Sale Securities, Cost Basis 9,303,808,000 8,890,389,000 9,303,808,000 8,890,389,000 9,035,418,000
Available-for-Sale Securities, Fair Value [Abstract]          
Available-for-Sale Securities, Fair Value 9,567,008,000 9,105,828,000 9,567,008,000 9,105,828,000 9,235,621,000
Available-for-Sale Securities, Gross Unrealized Gain (loss) [Abstract]          
Available-for-Sale Securities, Gross Unrealized Gain 334,343,000 337,838,000 334,343,000 337,838,000 292,592,000
Available-for-Sale Securities, Gross Unrealized Loss (14,035,000) (35,921,000) (14,035,000) (35,921,000) (36,560,000)
Available-for-Sale Securities, Other Than Temporary Impairment [Abstract]          
Available-for-Sale Securities, Other Than Temporary Impairment     (57,108,000) (86,478,000) (56,829,000)
Available-for-Sale Securities, Debt Maturities, Amortized Cost Basis [Abstract]          
Available-for-Sale Securities, Debt Maturities, Amortized Cost Basis 9,303,808,000   9,303,808,000    
Available-for-Sale Securities, Debt Maturities, Fair Value [Abstract]          
Available-for-Sale Securities 9,567,008,000 9,105,828,000 9,567,008,000 9,105,828,000 9,235,621,000
Available-for-Sale Securities, Debt Maturities, Nominal Yield[Abstract]          
Available-for-Sale Securities, Debt Maturities, Nominal Yield     3.76    
Available-for-Sale Securities, Gross Realized Gain (Loss) Disclosures [Abstract]          
Proceeds 771,536,000 594,990,000 1,411,220,000 915,138,000  
Gross realized gains 6,205,000 8,469,000 17,172,000 13,826,000  
Gross realized losses 3,654,000 0 7,809,000 0  
Related federal and state income tax expense 904,000 2,778,000 3,454,000 4,576,000  
Available-for-Sale Securities, Temporarily Impaired Securities [Abstract]          
Available-for-Sale Securities, Temporarily impaired Securities, Number of Securities 122 116 122 116 160
Available-for-Sale Securities, Temporarily impaired Securities, Fair Value[Abstract]          
Available-for-Sale Securities, Temporarily impaired Securities, Less Than 12, Fair Value 353,396,000 252,489,000 353,396,000 252,489,000 1,619,438,000
Available-for-Sale Securities, Temporarily impaired Securities, 12 Months or longer, Fair Value 478,779,000 660,906,000 478,779,000 660,906,000 632,705,000
Available-for-Sale Securities, Temporarily impaired Securities, Total, Fair Value 832,175,000 913,395,000 832,175,000 913,395,000 2,252,143,000
Available-for-Sale Securities, Temporarily impaired Securities, Unrealized Loss [Abstract]          
Available-for-Sale Securities, Temporarily impaired Securities, Less Than 12,Unrealized Loss 2,130,000 6,774,000 2,130,000 6,774,000 21,669,000
Available-for-Sale Securities, Temporarily impaired Securities, 12 Months or longer, Unrealized Loss 69,013,000 115,625,000 69,013,000 115,625,000 71,720,000
Available-for-Sale Securities, Temporarily impaired Securities, Total, Unrealized Loss 71,143,000 122,399,000 71,143,000 122,399,000 93,389,000
Available-for-Sale Securities, Portfolio Concentration Ratings, Amortized Cost [Abstract]          
Available-for-Sale Securities, Portfolio Concentration Rated US Governement or GSE, Amortized Cost 8,589,909,000   8,589,909,000    
Available-for-Sale Securities, Portfolio Concentration Rated AAA to AA, Amortized Cost 81,271,000   81,271,000    
Available-for-Sale Securities, Portfolio Concentration Rated A to BBB, Amortized Cost 107,984,000   107,984,000    
Available-for-Sale Securities, Portfolio Concentration Rated Below Investment Grade, Amortized Cost 483,980,000   483,980,000    
Available-for-Sale Securities, Portfolio Concentration Not RatedAmortized Cost 40,664,000   40,664,000    
Available-for-Sale Securities, Portfolio Concentration Total, Amortized Cost 9,303,808,000 8,890,389,000 9,303,808,000 8,890,389,000 9,035,418,000
Available-for-Sale Securities, Portfolio Concentration Ratings, Fair Value [Abstract]          
Available-for-Sale Securities, Portfolio Concentration Rated US Governement or GSE, Fair Value 8,894,792,000   8,894,792,000    
Available-for-Sale Securities, Portfolio Concentration Rated AAA to AA, Fair Value 82,460,000   82,460,000    
Available-for-Sale Securities, Portfolio Concentration Rated A to BBB, Fair Value 106,038,000   106,038,000    
Available-for-Sale Securities, Portfolio Concentration Rated Below Investment Grade, Fair Value 421,384,000   421,384,000    
Available-for-Sale Securities, Portfolio Concentration Rated Not Rated Fair Value 62,334,000   62,334,000    
Available-for-Sale Securities, Fair Value 9,567,008,000 9,105,828,000 9,567,008,000 9,105,828,000 9,235,621,000
Available-for-sale Securities [Member] | US Treasuries [Member]
         
Available-for-Sale Securities, Amortized cost Basis [Abstract]          
Available-for-Sale Securities, Cost Basis 1,001,000   1,001,000    
Available-for-Sale Securities, Fair Value [Abstract]          
Available-for-Sale Securities, Fair Value 1,003,000   1,003,000    
Available-for-Sale Securities, Gross Unrealized Gain (loss) [Abstract]          
Available-for-Sale Securities, Gross Unrealized Gain 2,000   2,000    
Available-for-Sale Securities, Gross Unrealized Loss 0   0    
Available-for-Sale Securities, Other Than Temporary Impairment [Abstract]          
Available-for-Sale Securities, Other Than Temporary Impairment     0    
Available-for-Sale Securities, Debt Maturities, Amortized Cost Basis [Abstract]          
Available-for-Sale Securities, Debt Maturities, Less Than One Year 1,001,000   1,001,000    
Available-for-Sale Securities, Debt Maturities, One to Five Years 0   0    
Available-for-Sale Securities, Debt Maturities, Six to Ten Years 0   0    
Available-for-Sale Securities, Debt Maturities, Over Ten Years 0   0    
Available-for-Sale Securities, Debt Maturities, Amortized Cost Basis 1,001,000   1,001,000    
Available-for-Sale Securities, Debt Maturities, Fair Value [Abstract]          
Available-for-Sale Securities, Debt Maturities, Less Than One Year, Fair Value 1,003,000   1,003,000    
Available-for-Sale Securities, Debt Maturities, One to Five YearsFair Value 0   0    
Available-for-Sale Securities, Debt Maturities, Six to Ten YearsFair Value 0   0    
Available-for-Sale Securities, Debt Maturities, Over Ten YearsFair Value 0   0    
Available-for-Sale Securities 1,003,000   1,003,000    
Available-for-Sale Securities, Debt Maturities, Amortized Cost Basis Weighted Average Maturity 1.84   1.84    
Available-for-Sale Securities, Debt Maturities, Nominal Yield[Abstract]          
Available-for-Sale Securities, Debt Maturities, Less Than One YearNominal Yield     0.55    
Available-for-Sale Securities, Debt Maturities, One to Five Years Nominal Yield     0    
Available-for-Sale Securities, Debt Maturities, Six to Ten Years Nominal Yield     0    
Available-for-Sale Securities, Debt Maturities, Over Ten Years Nominal Yield     0    
Available-for-Sale Securities, Debt Maturities, Nominal Yield     0.55    
Available-for-Sale Securities, Portfolio Concentration Ratings, Amortized Cost [Abstract]          
Available-for-Sale Securities, Portfolio Concentration Rated US Governement or GSE, Amortized Cost 1,001,000   1,001,000    
Available-for-Sale Securities, Portfolio Concentration Rated AAA to AA, Amortized Cost 0   0    
Available-for-Sale Securities, Portfolio Concentration Rated A to BBB, Amortized Cost 0   0    
Available-for-Sale Securities, Portfolio Concentration Rated Below Investment Grade, Amortized Cost 0   0    
Available-for-Sale Securities, Portfolio Concentration Not RatedAmortized Cost 0   0    
Available-for-Sale Securities, Portfolio Concentration Total, Amortized Cost 1,001,000   1,001,000    
Available-for-Sale Securities, Portfolio Concentration Ratings, Fair Value [Abstract]          
Available-for-Sale Securities, Portfolio Concentration Rated US Governement or GSE, Fair Value 1,003,000   1,003,000    
Available-for-Sale Securities, Portfolio Concentration Rated AAA to AA, Fair Value 0   0    
Available-for-Sale Securities, Portfolio Concentration Rated A to BBB, Fair Value 0   0    
Available-for-Sale Securities, Portfolio Concentration Rated Below Investment Grade, Fair Value 0   0    
Available-for-Sale Securities, Portfolio Concentration Rated Not Rated Fair Value 0   0    
Available-for-Sale Securities, Fair Value 1,003,000   1,003,000    
Available-for-sale Securities [Member] | Municipal And Other Tax Exempt Securities [Member]
         
Available-for-Sale Securities, Amortized cost Basis [Abstract]          
Available-for-Sale Securities, Cost Basis 68,502,000 66,053,000 68,502,000 66,053,000 72,190,000
Available-for-Sale Securities, Fair Value [Abstract]          
Available-for-Sale Securities, Fair Value 70,210,000 66,439,000 70,210,000 66,439,000 72,942,000
Available-for-Sale Securities, Gross Unrealized Gain (loss) [Abstract]          
Available-for-Sale Securities, Gross Unrealized Gain 2,375,000 1,460,000 2,375,000 1,460,000 1,172,000
Available-for-Sale Securities, Gross Unrealized Loss (146,000) (1,074,000) (146,000) (1,074,000) (315,000)
Available-for-Sale Securities, Other Than Temporary Impairment [Abstract]          
Available-for-Sale Securities, Other Than Temporary Impairment     (521,000) 0 (105,000)
Available-for-Sale Securities, Debt Maturities, Amortized Cost Basis [Abstract]          
Available-for-Sale Securities, Debt Maturities, Less Than One Year 744,000   744,000    
Available-for-Sale Securities, Debt Maturities, One to Five Years 6,941,000   6,941,000    
Available-for-Sale Securities, Debt Maturities, Six to Ten Years 12,575,000   12,575,000    
Available-for-Sale Securities, Debt Maturities, Over Ten Years 48,242,000   48,242,000    
Available-for-Sale Securities, Debt Maturities, Amortized Cost Basis 68,502,000   68,502,000    
Available-for-Sale Securities, Debt Maturities, Fair Value [Abstract]          
Available-for-Sale Securities, Debt Maturities, Less Than One Year, Fair Value 752,000   752,000    
Available-for-Sale Securities, Debt Maturities, One to Five YearsFair Value 8,077,000   8,077,000    
Available-for-Sale Securities, Debt Maturities, Six to Ten YearsFair Value 13,678,000   13,678,000    
Available-for-Sale Securities, Debt Maturities, Over Ten YearsFair Value 47,703,000   47,703,000    
Available-for-Sale Securities 70,210,000 66,439,000 70,210,000 66,439,000 72,942,000
Available-for-Sale Securities, Debt Maturities, Amortized Cost Basis Weighted Average Maturity 19.75   19.75    
Available-for-Sale Securities, Debt Maturities, Nominal Yield[Abstract]          
Available-for-Sale Securities, Debt Maturities, Less Than One YearNominal Yield     3.30    
Available-for-Sale Securities, Debt Maturities, One to Five Years Nominal Yield     4.12    
Available-for-Sale Securities, Debt Maturities, Six to Ten Years Nominal Yield     4.08    
Available-for-Sale Securities, Debt Maturities, Over Ten Years Nominal Yield     0.95    
Available-for-Sale Securities, Debt Maturities, Nominal Yield     1.87    
Available-for-Sale Securities, Temporarily Impaired Securities [Abstract]          
Available-for-Sale Securities, Temporarily impaired Securities, Number of Securities 51 23 51 23 42
Available-for-Sale Securities, Temporarily impaired Securities, Fair Value[Abstract]          
Available-for-Sale Securities, Temporarily impaired Securities, Less Than 12, Fair Value 24,065,000 32,325,000 24,065,000 32,325,000 22,271,000
Available-for-Sale Securities, Temporarily impaired Securities, 12 Months or longer, Fair Value 19,593,000 0 19,593,000 0 25,235,000
Available-for-Sale Securities, Temporarily impaired Securities, Total, Fair Value 43,658,000 32,325,000 43,658,000 32,325,000 47,506,000
Available-for-Sale Securities, Temporarily impaired Securities, Unrealized Loss [Abstract]          
Available-for-Sale Securities, Temporarily impaired Securities, Less Than 12,Unrealized Loss 301,000 1,074,000 301,000 1,074,000 171,000
Available-for-Sale Securities, Temporarily impaired Securities, 12 Months or longer, Unrealized Loss 366,000 0 366,000 0 249,000
Available-for-Sale Securities, Temporarily impaired Securities, Total, Unrealized Loss 667,000 1,074,000 667,000 1,074,000 420,000
Available-for-Sale Securities, Portfolio Concentration Ratings, Amortized Cost [Abstract]          
Available-for-Sale Securities, Portfolio Concentration Rated AAA to AA, Amortized Cost 39,996,000   39,996,000    
Available-for-Sale Securities, Portfolio Concentration Rated A to BBB, Amortized Cost 11,941,000   11,941,000    
Available-for-Sale Securities, Portfolio Concentration Rated Below Investment Grade, Amortized Cost 14,584,000   14,584,000    
Available-for-Sale Securities, Portfolio Concentration Not RatedAmortized Cost 1,981,000   1,981,000    
Available-for-Sale Securities, Portfolio Concentration Total, Amortized Cost 68,502,000 66,053,000 68,502,000 66,053,000 72,190,000
Available-for-Sale Securities, Portfolio Concentration Ratings, Fair Value [Abstract]          
Available-for-Sale Securities, Portfolio Concentration Rated AAA to AA, Fair Value 42,024,000   42,024,000    
Available-for-Sale Securities, Portfolio Concentration Rated A to BBB, Fair Value 11,986,000   11,986,000    
Available-for-Sale Securities, Portfolio Concentration Rated Below Investment Grade, Fair Value 14,063,000   14,063,000    
Available-for-Sale Securities, Portfolio Concentration Rated Not Rated Fair Value 2,137,000   2,137,000    
Available-for-Sale Securities, Fair Value 70,210,000 66,439,000 70,210,000 66,439,000 72,942,000
Available-for-sale Securities [Member] | Residential Mortgage Backed Securities [Member]
         
Available-for-Sale Securities, Amortized cost Basis [Abstract]          
Available-for-Sale Securities, Cost Basis 9,170,211,000 8,758,580,000 9,170,211,000 8,758,580,000 8,908,135,000
Available-for-Sale Securities, Fair Value [Abstract]          
Available-for-Sale Securities, Fair Value 9,407,011,000 8,959,235,000 9,407,011,000 8,959,235,000 9,091,118,000
Available-for-Sale Securities, Gross Unrealized Gain (loss) [Abstract]          
Available-for-Sale Securities, Gross Unrealized Gain 307,267,000 321,298,000 307,267,000 321,298,000 275,625,000
Available-for-Sale Securities, Gross Unrealized Loss (13,880,000) (34,165,000) (13,880,000) (34,165,000) (35,918,000)
Available-for-Sale Securities, Other Than Temporary Impairment [Abstract]          
Available-for-Sale Securities, Other Than Temporary Impairment     (56,587,000) (86,478,000) (56,724,000)
Available-for-Sale Securities, Debt Maturities, Fair Value [Abstract]          
Available-for-Sale Securities 9,407,011,000 8,959,235,000 9,407,011,000 8,959,235,000 9,091,118,000
Available-for-Sale Securities, Temporarily Impaired Securities [Abstract]          
Available-for-Sale Securities, Temporarily impaired Securities, Number of Securities 68 83 68 83 116
Available-for-Sale Securities, Temporarily impaired Securities, Fair Value[Abstract]          
Available-for-Sale Securities, Temporarily impaired Securities, Less Than 12, Fair Value 329,118,000 212,518,000 329,118,000 212,518,000 1,597,167,000
Available-for-Sale Securities, Temporarily impaired Securities, 12 Months or longer, Fair Value 458,193,000 657,271,000 458,193,000 657,271,000 604,592,000
Available-for-Sale Securities, Temporarily impaired Securities, Total, Fair Value 787,311,000 869,789,000 787,311,000 869,789,000 2,201,759,000
Available-for-Sale Securities, Temporarily impaired Securities, Unrealized Loss [Abstract]          
Available-for-Sale Securities, Temporarily impaired Securities, Less Than 12,Unrealized Loss 1,827,000 5,150,000 1,827,000 5,150,000 21,498,000
Available-for-Sale Securities, Temporarily impaired Securities, 12 Months or longer, Unrealized Loss 68,640,000 115,493,000 68,640,000 115,493,000 71,144,000
Available-for-Sale Securities, Temporarily impaired Securities, Total, Unrealized Loss 70,467,000 120,643,000 70,467,000 120,643,000 92,642,000
Available-for-Sale Securities, Portfolio Concentration Ratings, Amortized Cost [Abstract]          
Available-for-Sale Securities, Portfolio Concentration Rated US Governement or GSE, Amortized Cost 8,588,908,000   8,588,908,000    
Available-for-Sale Securities, Portfolio Concentration Rated AAA to AA, Amortized Cost 35,375,000   35,375,000    
Available-for-Sale Securities, Portfolio Concentration Rated A to BBB, Amortized Cost 76,532,000   76,532,000    
Available-for-Sale Securities, Portfolio Concentration Rated Below Investment Grade, Amortized Cost 469,396,000   469,396,000    
Available-for-Sale Securities, Portfolio Concentration Not RatedAmortized Cost 0   0    
Available-for-Sale Securities, Portfolio Concentration Total, Amortized Cost 9,170,211,000 8,758,580,000 9,170,211,000 8,758,580,000 8,908,135,000
Available-for-Sale Securities, Portfolio Concentration Ratings, Fair Value [Abstract]          
Available-for-Sale Securities, Portfolio Concentration Rated US Governement or GSE, Fair Value 8,893,789,000   8,893,789,000    
Available-for-Sale Securities, Portfolio Concentration Rated AAA to AA, Fair Value 34,543,000   34,543,000    
Available-for-Sale Securities, Portfolio Concentration Rated A to BBB, Fair Value 71,358,000   71,358,000    
Available-for-Sale Securities, Portfolio Concentration Rated Below Investment Grade, Fair Value 407,321,000   407,321,000    
Available-for-Sale Securities, Portfolio Concentration Rated Not Rated Fair Value 0   0    
Available-for-Sale Securities, Fair Value 9,407,011,000 8,959,235,000 9,407,011,000 8,959,235,000 9,091,118,000
Available-for-sale Securities [Member] | Residential Mortgage Backed Securities [Member] | US Government Agencies Debt Securities [Member]
         
Available-for-Sale Securities, Amortized cost Basis [Abstract]          
Available-for-Sale Securities, Cost Basis 8,588,908,000 7,909,107,000 8,588,908,000 7,909,107,000 8,193,705,000
Available-for-Sale Securities, Fair Value [Abstract]          
Available-for-Sale Securities, Fair Value 8,893,789,000 8,223,719,000 8,893,789,000 8,223,719,000 8,446,909,000
Available-for-Sale Securities, Gross Unrealized Gain (loss) [Abstract]          
Available-for-Sale Securities, Gross Unrealized Gain 306,708,000 319,762,000 306,708,000 319,762,000 274,702,000
Available-for-Sale Securities, Gross Unrealized Loss (1,827,000) (5,150,000) (1,827,000) (5,150,000) (21,498,000)
Available-for-Sale Securities, Other Than Temporary Impairment [Abstract]          
Available-for-Sale Securities, Other Than Temporary Impairment     0 0  
Available-for-Sale Securities, Debt Maturities, Fair Value [Abstract]          
Available-for-Sale Securities 8,893,789,000 8,223,719,000 8,893,789,000 8,223,719,000 8,446,909,000
Available-for-Sale Securities, Temporarily Impaired Securities [Abstract]          
Available-for-Sale Securities, Temporarily impaired Securities, Number of Securities 9 8 9 8 41
Available-for-Sale Securities, Temporarily impaired Securities, Fair Value[Abstract]          
Available-for-Sale Securities, Temporarily impaired Securities, Less Than 12, Fair Value 329,118,000 212,518,000 329,118,000 212,518,000 1,597,167,000
Available-for-Sale Securities, Temporarily impaired Securities, 12 Months or longer, Fair Value 0 0 0 0 0
Available-for-Sale Securities, Temporarily impaired Securities, Total, Fair Value 32,918,000 212,518,000 32,918,000 212,518,000 1,597,167,000
Available-for-Sale Securities, Temporarily impaired Securities, Unrealized Loss [Abstract]          
Available-for-Sale Securities, Temporarily impaired Securities, Less Than 12,Unrealized Loss 1,827,000 5,150,000 1,827,000 5,150,000 21,498,000
Available-for-Sale Securities, Temporarily impaired Securities, 12 Months or longer, Unrealized Loss 0   0   0
Available-for-Sale Securities, Temporarily impaired Securities, Total, Unrealized Loss 1,827,000 5,150,000 1,827,000 5,150,000 21,498,000
Available-for-Sale Securities, Portfolio Concentration Ratings, Amortized Cost [Abstract]          
Available-for-Sale Securities, Portfolio Concentration Rated US Governement or GSE, Amortized Cost 8,588,908,000   8,588,908,000    
Available-for-Sale Securities, Portfolio Concentration Rated AAA to AA, Amortized Cost 0   0    
Available-for-Sale Securities, Portfolio Concentration Rated A to BBB, Amortized Cost 0   0    
Available-for-Sale Securities, Portfolio Concentration Rated Below Investment Grade, Amortized Cost 0   0    
Available-for-Sale Securities, Portfolio Concentration Not RatedAmortized Cost 0   0    
Available-for-Sale Securities, Portfolio Concentration Total, Amortized Cost 8,588,908,000 7,909,107,000 8,588,908,000 7,909,107,000 8,193,705,000
Available-for-Sale Securities, Portfolio Concentration Ratings, Fair Value [Abstract]          
Available-for-Sale Securities, Portfolio Concentration Rated US Governement or GSE, Fair Value 8,893,789,000   8,893,789,000    
Available-for-Sale Securities, Portfolio Concentration Rated AAA to AA, Fair Value 0   0    
Available-for-Sale Securities, Portfolio Concentration Rated A to BBB, Fair Value 0   0    
Available-for-Sale Securities, Portfolio Concentration Rated Below Investment Grade, Fair Value 0   0    
Available-for-Sale Securities, Portfolio Concentration Rated Not Rated Fair Value 0   0    
Available-for-Sale Securities, Fair Value 8,893,789,000 8,223,719,000 8,893,789,000 8,223,719,000 8,446,909,000
Available-for-sale Securities [Member] | Residential Mortgage Backed Securities [Member] | US Government Agencies Debt Securities [Member] | FNMA [Member]
         
Available-for-Sale Securities, Amortized cost Basis [Abstract]          
Available-for-Sale Securities, Cost Basis 5,359,939,000 4,148,758,000 5,359,939,000 4,148,758,000 4,791,438,000
Available-for-Sale Securities, Fair Value [Abstract]          
Available-for-Sale Securities, Fair Value 5,524,849,000 4,319,324,000 5,524,849,000 4,319,324,000 4,925,693,000
Available-for-Sale Securities, Gross Unrealized Gain (loss) [Abstract]          
Available-for-Sale Securities, Gross Unrealized Gain 166,016,000 174,183,000 166,016,000 174,183,000 147,024,000
Available-for-Sale Securities, Gross Unrealized Loss (1,106,000) (3,617,000) (1,106,000) (3,617,000) (12,769,000)
Available-for-Sale Securities, Other Than Temporary Impairment [Abstract]          
Available-for-Sale Securities, Other Than Temporary Impairment     0 0 0
Available-for-Sale Securities, Debt Maturities, Fair Value [Abstract]          
Available-for-Sale Securities 5,524,849,000 4,319,324,000 5,524,849,000 4,319,324,000 4,925,693,000
Available-for-Sale Securities, Temporarily Impaired Securities [Abstract]          
Available-for-Sale Securities, Temporarily impaired Securities, Number of Securities 7 6 7 6 26
Available-for-Sale Securities, Temporarily impaired Securities, Fair Value[Abstract]          
Available-for-Sale Securities, Temporarily impaired Securities, Less Than 12, Fair Value 230,949,000 166,825,000 230,949,000 166,825,000 1,099,710,000
Available-for-Sale Securities, Temporarily impaired Securities, 12 Months or longer, Fair Value 0 0 0 0 0
Available-for-Sale Securities, Temporarily impaired Securities, Total, Fair Value 230,949,000 166,825,000 230,949,000 166,825,000 109,971,000
Available-for-Sale Securities, Temporarily impaired Securities, Unrealized Loss [Abstract]          
Available-for-Sale Securities, Temporarily impaired Securities, Less Than 12,Unrealized Loss 1,106,000 3,617,000 1,106,000 3,617,000 12,769,000
Available-for-Sale Securities, Temporarily impaired Securities, 12 Months or longer, Unrealized Loss 0 0 0 0 0
Available-for-Sale Securities, Temporarily impaired Securities, Total, Unrealized Loss 1,106,000 3,617,000 1,106,000 3,617,000 12,769,000
Available-for-Sale Securities, Portfolio Concentration Ratings, Amortized Cost [Abstract]          
Available-for-Sale Securities, Portfolio Concentration Rated US Governement or GSE, Amortized Cost 5,359,939,000   5,359,939,000    
Available-for-Sale Securities, Portfolio Concentration Rated AAA to AA, Amortized Cost 0   0    
Available-for-Sale Securities, Portfolio Concentration Rated A to BBB, Amortized Cost 0   0    
Available-for-Sale Securities, Portfolio Concentration Rated Below Investment Grade, Amortized Cost 0   0    
Available-for-Sale Securities, Portfolio Concentration Not RatedAmortized Cost 0   0    
Available-for-Sale Securities, Portfolio Concentration Total, Amortized Cost 5,359,939,000 4,148,758,000 5,359,939,000 4,148,758,000 4,791,438,000
Available-for-Sale Securities, Portfolio Concentration Ratings, Fair Value [Abstract]          
Available-for-Sale Securities, Portfolio Concentration Rated US Governement or GSE, Fair Value 5,524,849,000   5,524,849,000    
Available-for-Sale Securities, Portfolio Concentration Rated AAA to AA, Fair Value 0   0    
Available-for-Sale Securities, Portfolio Concentration Rated A to BBB, Fair Value 0   0    
Available-for-Sale Securities, Portfolio Concentration Rated Below Investment Grade, Fair Value 0   0    
Available-for-Sale Securities, Portfolio Concentration Rated Not Rated Fair Value 0   0    
Available-for-Sale Securities, Fair Value 5,524,849,000 4,319,324,000 5,524,849,000 4,319,324,000 4,925,693,000
Available-for-sale Securities [Member] | Residential Mortgage Backed Securities [Member] | US Government Agencies Debt Securities [Member] | FHLMC [Member]
         
Available-for-Sale Securities, Amortized cost Basis [Abstract]          
Available-for-Sale Securities, Cost Basis 2,447,830,000 2,680,437,000 2,447,830,000 2,680,437,000 2,545,208,000
Available-for-Sale Securities, Fair Value [Abstract]          
Available-for-Sale Securities, Fair Value 2,544,684,000 2,776,620,000 2,544,684,000 2,776,620,000 2,620,066,000
Available-for-Sale Securities, Gross Unrealized Gain (loss) [Abstract]          
Available-for-Sale Securities, Gross Unrealized Gain 97,575,000 96,183,000 97,575,000 96,183,000 83,341,000
Available-for-Sale Securities, Gross Unrealized Loss (721,000) 0 (721,000) 0 (8,483,000)
Available-for-Sale Securities, Other Than Temporary Impairment [Abstract]          
Available-for-Sale Securities, Other Than Temporary Impairment     0 0 0
Available-for-Sale Securities, Debt Maturities, Fair Value [Abstract]          
Available-for-Sale Securities 2,544,684,000 2,776,620,000 2,544,684,000 2,776,620,000 2,620,066,000
Available-for-Sale Securities, Temporarily Impaired Securities [Abstract]          
Available-for-Sale Securities, Temporarily impaired Securities, Number of Securities 2   2   12
Available-for-Sale Securities, Temporarily impaired Securities, Fair Value[Abstract]          
Available-for-Sale Securities, Temporarily impaired Securities, Less Than 12, Fair Value 98,169,000   98,169,000   491,776,000
Available-for-Sale Securities, Temporarily impaired Securities, 12 Months or longer, Fair Value 0   0   0
Available-for-Sale Securities, Temporarily impaired Securities, Total, Fair Value 98,169,000   98,169,000   491,776,000
Available-for-Sale Securities, Temporarily impaired Securities, Unrealized Loss [Abstract]          
Available-for-Sale Securities, Temporarily impaired Securities, Less Than 12,Unrealized Loss 721,000   721,000   8,483,000
Available-for-Sale Securities, Temporarily impaired Securities, 12 Months or longer, Unrealized Loss 0   0   0
Available-for-Sale Securities, Temporarily impaired Securities, Total, Unrealized Loss 721,000   721,000   8,483,000
Available-for-Sale Securities, Portfolio Concentration Ratings, Amortized Cost [Abstract]          
Available-for-Sale Securities, Portfolio Concentration Rated US Governement or GSE, Amortized Cost 2,447,830,000   2,447,830,000    
Available-for-Sale Securities, Portfolio Concentration Rated AAA to AA, Amortized Cost 0   0    
Available-for-Sale Securities, Portfolio Concentration Rated A to BBB, Amortized Cost 0   0    
Available-for-Sale Securities, Portfolio Concentration Rated Below Investment Grade, Amortized Cost 0   0    
Available-for-Sale Securities, Portfolio Concentration Not RatedAmortized Cost 0   0    
Available-for-Sale Securities, Portfolio Concentration Total, Amortized Cost 2,447,830,000 2,680,437,000 2,447,830,000 2,680,437,000 2,545,208,000
Available-for-Sale Securities, Portfolio Concentration Ratings, Fair Value [Abstract]          
Available-for-Sale Securities, Portfolio Concentration Rated US Governement or GSE, Fair Value 2,544,684,000   2,544,684,000    
Available-for-Sale Securities, Portfolio Concentration Rated AAA to AA, Fair Value 0   0    
Available-for-Sale Securities, Portfolio Concentration Rated A to BBB, Fair Value 0   0    
Available-for-Sale Securities, Portfolio Concentration Rated Below Investment Grade, Fair Value 0   0    
Available-for-Sale Securities, Portfolio Concentration Rated Not Rated Fair Value 0   0    
Available-for-Sale Securities, Fair Value 2,544,684,000 2,776,620,000 2,544,684,000 2,776,620,000 2,620,066,000
Available-for-sale Securities [Member] | Residential Mortgage Backed Securities [Member] | US Government Agencies Debt Securities [Member] | GNMA [Member]
         
Available-for-Sale Securities, Amortized cost Basis [Abstract]          
Available-for-Sale Securities, Cost Basis 704,168,000 972,348,000 704,168,000 972,348,000 765,046,000
Available-for-Sale Securities, Fair Value [Abstract]          
Available-for-Sale Securities, Fair Value 742,411,000 1,011,522,000 742,411,000 1,011,522,000 801,993,000
Available-for-Sale Securities, Gross Unrealized Gain (loss) [Abstract]          
Available-for-Sale Securities, Gross Unrealized Gain 38,243,000 40,707,000 38,243,000 40,707,000 37,193,000
Available-for-Sale Securities, Gross Unrealized Loss 0 (1,533,000) 0 (1,533,000) (246,000)
Available-for-Sale Securities, Other Than Temporary Impairment [Abstract]          
Available-for-Sale Securities, Other Than Temporary Impairment     0 0 0
Available-for-Sale Securities, Debt Maturities, Fair Value [Abstract]          
Available-for-Sale Securities 742,411,000 1,011,522,000 742,411,000 1,011,522,000 801,993,000
Available-for-Sale Securities, Temporarily Impaired Securities [Abstract]          
Available-for-Sale Securities, Temporarily impaired Securities, Number of Securities   2   2 3
Available-for-Sale Securities, Temporarily impaired Securities, Fair Value[Abstract]          
Available-for-Sale Securities, Temporarily impaired Securities, Less Than 12, Fair Value   45,693,000   45,693,000 5,681,000
Available-for-Sale Securities, Temporarily impaired Securities, 12 Months or longer, Fair Value   0   0 0
Available-for-Sale Securities, Temporarily impaired Securities, Total, Fair Value   45,693,000   45,693,000 5,681,000
Available-for-Sale Securities, Temporarily impaired Securities, Unrealized Loss [Abstract]          
Available-for-Sale Securities, Temporarily impaired Securities, Less Than 12,Unrealized Loss   1,533,000   1,533,000 246,000
Available-for-Sale Securities, Temporarily impaired Securities, 12 Months or longer, Unrealized Loss   0   0 0
Available-for-Sale Securities, Temporarily impaired Securities, Total, Unrealized Loss   1,533,000   1,533,000 246,000
Available-for-Sale Securities, Portfolio Concentration Ratings, Amortized Cost [Abstract]          
Available-for-Sale Securities, Portfolio Concentration Rated US Governement or GSE, Amortized Cost 704,168,000   704,168,000    
Available-for-Sale Securities, Portfolio Concentration Rated AAA to AA, Amortized Cost 0   0    
Available-for-Sale Securities, Portfolio Concentration Rated A to BBB, Amortized Cost 0   0    
Available-for-Sale Securities, Portfolio Concentration Not RatedAmortized Cost 0   0    
Available-for-Sale Securities, Portfolio Concentration Total, Amortized Cost 704,168,000 972,348,000 704,168,000 972,348,000 765,046,000
Available-for-Sale Securities, Portfolio Concentration Ratings, Fair Value [Abstract]          
Available-for-Sale Securities, Portfolio Concentration Rated US Governement or GSE, Fair Value 742,411,000   742,411,000    
Available-for-Sale Securities, Portfolio Concentration Rated AAA to AA, Fair Value 0   0    
Available-for-Sale Securities, Portfolio Concentration Rated A to BBB, Fair Value 0   0    
Available-for-Sale Securities, Portfolio Concentration Rated Below Investment Grade, Fair Value 0   0    
Available-for-Sale Securities, Portfolio Concentration Rated Not Rated Fair Value 0   0    
Available-for-Sale Securities, Fair Value 742,411,000 1,011,522,000 742,411,000 1,011,522,000 801,993,000
Available-for-sale Securities [Member] | Residential Mortgage Backed Securities [Member] | US Government Agencies Debt Securities [Member] | Other Agency [Member]
         
Available-for-Sale Securities, Amortized cost Basis [Abstract]          
Available-for-Sale Securities, Cost Basis 76,971,000 107,564,000 76,971,000 107,564,000 92,013,000
Available-for-Sale Securities, Fair Value [Abstract]          
Available-for-Sale Securities, Fair Value 81,845,000 116,253,000 81,845,000 116,253,000 99,157,000
Available-for-Sale Securities, Gross Unrealized Gain (loss) [Abstract]          
Available-for-Sale Securities, Gross Unrealized Gain 4,874,000 8,689,000 4,874,000 8,689,000 7,144,000
Available-for-Sale Securities, Gross Unrealized Loss 0 0 0 0 0
Available-for-Sale Securities, Other Than Temporary Impairment [Abstract]          
Available-for-Sale Securities, Other Than Temporary Impairment     0 0 0
Available-for-Sale Securities, Debt Maturities, Fair Value [Abstract]          
Available-for-Sale Securities 81,845,000 116,253,000 81,845,000 116,253,000 99,157,000
Available-for-Sale Securities, Portfolio Concentration Ratings, Amortized Cost [Abstract]          
Available-for-Sale Securities, Portfolio Concentration Rated US Governement or GSE, Amortized Cost 76,971,000   76,971,000    
Available-for-Sale Securities, Portfolio Concentration Rated AAA to AA, Amortized Cost 0   0    
Available-for-Sale Securities, Portfolio Concentration Rated A to BBB, Amortized Cost 0   0    
Available-for-Sale Securities, Portfolio Concentration Rated Below Investment Grade, Amortized Cost 0   0    
Available-for-Sale Securities, Portfolio Concentration Not RatedAmortized Cost 0   0    
Available-for-Sale Securities, Portfolio Concentration Total, Amortized Cost 76,971,000 107,564,000 76,971,000 107,564,000 92,013,000
Available-for-Sale Securities, Portfolio Concentration Ratings, Fair Value [Abstract]          
Available-for-Sale Securities, Portfolio Concentration Rated US Governement or GSE, Fair Value 81,845,000   81,845,000    
Available-for-Sale Securities, Portfolio Concentration Rated AAA to AA, Fair Value 0   0    
Available-for-Sale Securities, Portfolio Concentration Rated A to BBB, Fair Value 0   0    
Available-for-Sale Securities, Portfolio Concentration Rated Below Investment Grade, Fair Value 0   0    
Available-for-Sale Securities, Portfolio Concentration Rated Not Rated Fair Value 0   0    
Available-for-Sale Securities, Fair Value 81,845,000 116,253,000 81,845,000 116,253,000 99,157,000
Available-for-sale Securities [Member] | Residential Mortgage Backed Securities [Member] | Private Issue [Member]
         
Available-for-Sale Securities, Amortized cost Basis [Abstract]          
Available-for-Sale Securities, Cost Basis 581,303,000 849,473,000 581,303,000 849,473,000 714,430,000
Available-for-Sale Securities, Fair Value [Abstract]          
Available-for-Sale Securities, Fair Value 513,222,000 735,516,000 513,222,000 735,516,000 644,209,000
Available-for-Sale Securities, Gross Unrealized Gain (loss) [Abstract]          
Available-for-Sale Securities, Gross Unrealized Gain 559,000 1,536,000 559,000 1,536,000 923,000
Available-for-Sale Securities, Gross Unrealized Loss (12,053,000) (29,015,000) (12,053,000) (29,015,000) (14,420,000)
Available-for-Sale Securities, Other Than Temporary Impairment [Abstract]          
Available-for-Sale Securities, Other Than Temporary Impairment     (56,587,000) (86,478,000) (56,724,000)
Available-for-Sale Securities, Debt Maturities, Fair Value [Abstract]          
Available-for-Sale Securities 513,222,000 735,516,000 513,222,000 735,516,000 644,209,000
Available-for-Sale Securities, Temporarily Impaired Securities [Abstract]          
Available-for-Sale Securities, Temporarily impaired Securities, Number of Securities 59 75 59 75 75
Available-for-Sale Securities, Temporarily impaired Securities, Fair Value[Abstract]          
Available-for-Sale Securities, Temporarily impaired Securities, Less Than 12, Fair Value 0 0 0 0 0
Available-for-Sale Securities, Temporarily impaired Securities, 12 Months or longer, Fair Value 458,193,000 657,271,000 458,193,000 657,271,000 604,592,000
Available-for-Sale Securities, Temporarily impaired Securities, Total, Fair Value 458,193,000 657,271,000 458,193,000 657,271,000 604,592,000
Available-for-Sale Securities, Temporarily impaired Securities, Unrealized Loss [Abstract]          
Available-for-Sale Securities, Temporarily impaired Securities, Less Than 12,Unrealized Loss 0 0 0 0 0
Available-for-Sale Securities, Temporarily impaired Securities, 12 Months or longer, Unrealized Loss 68,640,000 115,493,000 68,640,000 115,493,000 71,144,000
Available-for-Sale Securities, Temporarily impaired Securities, Total, Unrealized Loss 68,640,000 115,493,000 68,640,000 115,493,000 71,144,000
Available-for-Sale Securities, Portfolio Concentration Ratings, Amortized Cost [Abstract]          
Available-for-Sale Securities, Portfolio Concentration Rated US Governement or GSE, Amortized Cost 0   0    
Available-for-Sale Securities, Portfolio Concentration Rated AAA to AA, Amortized Cost 35,375,000   35,375,000    
Available-for-Sale Securities, Portfolio Concentration Rated A to BBB, Amortized Cost 76,532,000   76,532,000    
Available-for-Sale Securities, Portfolio Concentration Rated Below Investment Grade, Amortized Cost 469,396,000   469,396,000    
Available-for-Sale Securities, Portfolio Concentration Not RatedAmortized Cost 0   0    
Available-for-Sale Securities, Portfolio Concentration Total, Amortized Cost 581,303,000 849,473,000 581,303,000 849,473,000 714,430,000
Available-for-Sale Securities, Portfolio Concentration Ratings, Fair Value [Abstract]          
Available-for-Sale Securities, Portfolio Concentration Rated US Governement or GSE, Fair Value 0   0    
Available-for-Sale Securities, Portfolio Concentration Rated AAA to AA, Fair Value 34,543,000   34,543,000    
Available-for-Sale Securities, Portfolio Concentration Rated A to BBB, Fair Value 71,358,000   71,358,000    
Available-for-Sale Securities, Portfolio Concentration Rated Below Investment Grade, Fair Value 407,321,000   407,321,000    
Available-for-Sale Securities, Portfolio Concentration Rated Not Rated Fair Value 0   0    
Available-for-Sale Securities, Fair Value 513,222,000 735,516,000 513,222,000 735,516,000 644,209,000
Available-for-sale Securities [Member] | Residential Mortgage Backed Securities [Member] | Private Issue [Member] | Alt A [Member]
         
Available-for-Sale Securities, Amortized cost Basis [Abstract]          
Available-for-Sale Securities, Cost Basis 195,932,000 230,058,000 195,932,000 230,058,000 220,332,000
Available-for-Sale Securities, Fair Value [Abstract]          
Available-for-Sale Securities, Fair Value 166,757,000 176,489,000 166,757,000 176,489,000 186,674,000
Available-for-Sale Securities, Gross Unrealized Gain (loss) [Abstract]          
Available-for-Sale Securities, Gross Unrealized Gain 46,000 0 46,000 0 0
Available-for-Sale Securities, Gross Unrealized Loss (104,000) (1,350,000) (104,000) (1,350,000) (353,000)
Available-for-Sale Securities, Other Than Temporary Impairment [Abstract]          
Available-for-Sale Securities, Other Than Temporary Impairment     (29,117,000) (52,219,000) (33,305,000)
Available-for-Sale Securities, Debt Maturities, Fair Value [Abstract]          
Available-for-Sale Securities 166,757,000 176,489,000 166,757,000 176,489,000 186,674,000
Available-for-Sale Securities, Temporarily Impaired Securities [Abstract]          
Available-for-Sale Securities, Temporarily impaired Securities, Number of Securities 20 20 20 20 22
Available-for-Sale Securities, Temporarily impaired Securities, Fair Value[Abstract]          
Available-for-Sale Securities, Temporarily impaired Securities, Less Than 12, Fair Value 0 0 0 0 0
Available-for-Sale Securities, Temporarily impaired Securities, 12 Months or longer, Fair Value 156,796,000 176,489,000 156,796,000 176,489,000 186,675,000
Available-for-Sale Securities, Temporarily impaired Securities, Total, Fair Value 156,796,000 176,489,000 156,796,000 176,489,000 186,675,000
Available-for-Sale Securities, Temporarily impaired Securities, Unrealized Loss [Abstract]          
Available-for-Sale Securities, Temporarily impaired Securities, Less Than 12,Unrealized Loss 0 0 0 0 0
Available-for-Sale Securities, Temporarily impaired Securities, 12 Months or longer, Unrealized Loss 29,221,000 53,569,000 29,221,000 53,569,000 33,658,000
Available-for-Sale Securities, Temporarily impaired Securities, Total, Unrealized Loss 29,221,000 53,569,000 29,221,000 53,569,000 33,658,000
Available-for-Sale Securities, Portfolio Concentration Ratings, Amortized Cost [Abstract]          
Available-for-Sale Securities, Portfolio Concentration Rated US Governement or GSE, Amortized Cost 0   0    
Available-for-Sale Securities, Portfolio Concentration Rated AAA to AA, Amortized Cost 3,269,000   3,269,000    
Available-for-Sale Securities, Portfolio Concentration Rated A to BBB, Amortized Cost 9,914,000   9,914,000    
Available-for-Sale Securities, Portfolio Concentration Rated Below Investment Grade, Amortized Cost 182,749,000   182,749,000    
Available-for-Sale Securities, Portfolio Concentration Not RatedAmortized Cost 0   0    
Available-for-Sale Securities, Portfolio Concentration Total, Amortized Cost 195,932,000 230,058,000 195,932,000 230,058,000 220,332,000
Available-for-Sale Securities, Portfolio Concentration Ratings, Fair Value [Abstract]          
Available-for-Sale Securities, Portfolio Concentration Rated US Governement or GSE, Fair Value 0   0    
Available-for-Sale Securities, Portfolio Concentration Rated AAA to AA, Fair Value 3,164,000   3,164,000    
Available-for-Sale Securities, Portfolio Concentration Rated A to BBB, Fair Value 9,961,000   9,961,000    
Available-for-Sale Securities, Portfolio Concentration Rated Below Investment Grade, Fair Value 153,632,000   153,632,000    
Available-for-Sale Securities, Portfolio Concentration Rated Not Rated Fair Value 0   0    
Available-for-Sale Securities, Fair Value 166,757,000 176,489,000 166,757,000 176,489,000 186,674,000
Available-for-sale Securities [Member] | Residential Mortgage Backed Securities [Member] | Private Issue [Member] | Jumbo A Loans [Member]
         
Available-for-Sale Securities, Amortized cost Basis [Abstract]          
Available-for-Sale Securities, Cost Basis 385,371,000 619,415,000 385,371,000 619,415,000 494,098,000
Available-for-Sale Securities, Fair Value [Abstract]          
Available-for-Sale Securities, Fair Value 346,465,000 559,027,000 346,465,000 559,027,000 457,535,000
Available-for-Sale Securities, Gross Unrealized Gain (loss) [Abstract]          
Available-for-Sale Securities, Gross Unrealized Gain 513,000 1,536,000 513,000 1,536,000 923,000
Available-for-Sale Securities, Gross Unrealized Loss (11,949,000) (27,665,000) (11,949,000) (27,665,000) (14,067,000)
Available-for-Sale Securities, Other Than Temporary Impairment [Abstract]          
Available-for-Sale Securities, Other Than Temporary Impairment     (27,470,000) (34,259,000) (23,419,000)
Available-for-Sale Securities, Debt Maturities, Fair Value [Abstract]          
Available-for-Sale Securities 346,465,000 559,027,000 346,465,000 559,027,000 457,535,000
Available-for-Sale Securities, Temporarily Impaired Securities [Abstract]          
Available-for-Sale Securities, Temporarily impaired Securities, Number of Securities 39 55 39 55 53
Available-for-Sale Securities, Temporarily impaired Securities, Fair Value[Abstract]          
Available-for-Sale Securities, Temporarily impaired Securities, Less Than 12, Fair Value 0 0 0 0 0
Available-for-Sale Securities, Temporarily impaired Securities, 12 Months or longer, Fair Value 301,397,000 480,782,000 301,397,000 480,782,000 417,917,000
Available-for-Sale Securities, Temporarily impaired Securities, Total, Fair Value 301,397,000 48,782,000 301,397,000 48,782,000 417,917,000
Available-for-Sale Securities, Temporarily impaired Securities, Unrealized Loss [Abstract]          
Available-for-Sale Securities, Temporarily impaired Securities, Less Than 12,Unrealized Loss 0 0 0 0 0
Available-for-Sale Securities, Temporarily impaired Securities, 12 Months or longer, Unrealized Loss 39,419,000 61,924,000 39,419,000 61,924,000 37,486,000
Available-for-Sale Securities, Temporarily impaired Securities, Total, Unrealized Loss 39,419,000 61,924,000 39,419,000 61,924,000 37,486,000
Available-for-Sale Securities, Portfolio Concentration Ratings, Amortized Cost [Abstract]          
Available-for-Sale Securities, Portfolio Concentration Rated US Governement or GSE, Amortized Cost 0   0    
Available-for-Sale Securities, Portfolio Concentration Rated AAA to AA, Amortized Cost 32,106,000   32,106,000    
Available-for-Sale Securities, Portfolio Concentration Rated A to BBB, Amortized Cost 66,618,000   66,618,000    
Available-for-Sale Securities, Portfolio Concentration Rated Below Investment Grade, Amortized Cost 28,647,000   28,647,000    
Available-for-Sale Securities, Portfolio Concentration Not RatedAmortized Cost 0   0    
Available-for-Sale Securities, Portfolio Concentration Total, Amortized Cost 385,371,000 619,415,000 385,371,000 619,415,000 494,098,000
Available-for-Sale Securities, Portfolio Concentration Ratings, Fair Value [Abstract]          
Available-for-Sale Securities, Portfolio Concentration Rated US Governement or GSE, Fair Value 0   0    
Available-for-Sale Securities, Portfolio Concentration Rated AAA to AA, Fair Value 31,379,000   31,379,000    
Available-for-Sale Securities, Portfolio Concentration Rated A to BBB, Fair Value 61,397,000   61,397,000    
Available-for-Sale Securities, Portfolio Concentration Rated Below Investment Grade, Fair Value 253,689,000   253,689,000    
Available-for-Sale Securities, Portfolio Concentration Rated Not Rated Fair Value 0   0    
Available-for-Sale Securities, Fair Value 346,465,000 559,027,000 346,465,000 559,027,000 457,535,000
Available-for-sale Securities [Member] | Other Debt Obligations [Member]
         
Available-for-Sale Securities, Amortized cost Basis [Abstract]          
Available-for-Sale Securities, Cost Basis 5,900,000 12,971,000 5,900,000 12,971,000 6,401,000
Available-for-Sale Securities, Fair Value [Abstract]          
Available-for-Sale Securities, Fair Value 5,893,000 13,064,000 5,893,000 13,064,000 6,401,000
Available-for-Sale Securities, Gross Unrealized Gain (loss) [Abstract]          
Available-for-Sale Securities, Gross Unrealized Gain 0 120,000 0 120,000 0
Available-for-Sale Securities, Gross Unrealized Loss (7,000) (27,000) (7,000) (27,000) 0
Available-for-Sale Securities, Other Than Temporary Impairment [Abstract]          
Available-for-Sale Securities, Other Than Temporary Impairment     0 0 0
Available-for-Sale Securities, Debt Maturities, Amortized Cost Basis [Abstract]          
Available-for-Sale Securities, Debt Maturities, Less Than One Year 0   0    
Available-for-Sale Securities, Debt Maturities, One to Five Years 0   0    
Available-for-Sale Securities, Debt Maturities, Six to Ten Years 0   0    
Available-for-Sale Securities, Debt Maturities, Over Ten Years 5,900,000   5,900,000    
Available-for-Sale Securities, Debt Maturities, Amortized Cost Basis 5,900,000   5,900,000    
Available-for-Sale Securities, Debt Maturities, Fair Value [Abstract]          
Available-for-Sale Securities, Debt Maturities, Less Than One Year, Fair Value 0   0    
Available-for-Sale Securities, Debt Maturities, One to Five YearsFair Value 0   0    
Available-for-Sale Securities, Debt Maturities, Six to Ten YearsFair Value 0   0    
Available-for-Sale Securities, Debt Maturities, Over Ten YearsFair Value 5,893,000   5,893,000    
Available-for-Sale Securities 5,893,000 13,064,000 5,893,000 13,064,000 6,401,000
Available-for-Sale Securities, Debt Maturities, Amortized Cost Basis Weighted Average Maturity 32.46   32.46    
Available-for-Sale Securities, Debt Maturities, Nominal Yield[Abstract]          
Available-for-Sale Securities, Debt Maturities, Less Than One YearNominal Yield     0    
Available-for-Sale Securities, Debt Maturities, One to Five Years Nominal Yield     0    
Available-for-Sale Securities, Debt Maturities, Six to Ten Years Nominal Yield     0    
Available-for-Sale Securities, Debt Maturities, Over Ten Years Nominal Yield     1.71    
Available-for-Sale Securities, Debt Maturities, Nominal Yield     1.71    
Available-for-Sale Securities, Temporarily Impaired Securities [Abstract]          
Available-for-Sale Securities, Temporarily impaired Securities, Number of Securities 2 7 2 7 0
Available-for-Sale Securities, Temporarily impaired Securities, Fair Value[Abstract]          
Available-for-Sale Securities, Temporarily impaired Securities, Less Than 12, Fair Value 0 4,965,000 0 4,965,000 0
Available-for-Sale Securities, Temporarily impaired Securities, 12 Months or longer, Fair Value 993,000 29,000 993,000 29,000 0
Available-for-Sale Securities, Temporarily impaired Securities, Total, Fair Value 993,000 4,994,000 993,000 4,994,000 0
Available-for-Sale Securities, Temporarily impaired Securities, Unrealized Loss [Abstract]          
Available-for-Sale Securities, Temporarily impaired Securities, Less Than 12,Unrealized Loss 0 27,000 0 27,000 0
Available-for-Sale Securities, Temporarily impaired Securities, 12 Months or longer, Unrealized Loss 7,000 0 7,000 0 0
Available-for-Sale Securities, Temporarily impaired Securities, Total, Unrealized Loss 7,000 27,000 7,000 27,000 0
Available-for-Sale Securities, Portfolio Concentration Ratings, Amortized Cost [Abstract]          
Available-for-Sale Securities, Portfolio Concentration Rated US Governement or GSE, Amortized Cost 5,900,000   5,900,000    
Available-for-Sale Securities, Portfolio Concentration Rated AAA to AA, Amortized Cost 0   0    
Available-for-Sale Securities, Portfolio Concentration Rated A to BBB, Amortized Cost 0   0    
Available-for-Sale Securities, Portfolio Concentration Rated Below Investment Grade, Amortized Cost 0   0    
Available-for-Sale Securities, Portfolio Concentration Not RatedAmortized Cost 0   0    
Available-for-Sale Securities, Portfolio Concentration Total, Amortized Cost 5,900,000 12,971,000 5,900,000 12,971,000 6,401,000
Available-for-Sale Securities, Portfolio Concentration Ratings, Fair Value [Abstract]          
Available-for-Sale Securities, Portfolio Concentration Rated US Governement or GSE, Fair Value 0   0    
Available-for-Sale Securities, Portfolio Concentration Rated AAA to AA, Fair Value 5,893,000   5,893,000    
Available-for-Sale Securities, Portfolio Concentration Rated A to BBB, Fair Value 0   0    
Available-for-Sale Securities, Portfolio Concentration Rated Below Investment Grade, Fair Value 0   0    
Available-for-Sale Securities, Portfolio Concentration Rated Not Rated Fair Value 0   0    
Available-for-Sale Securities, Fair Value 5,893,000 13,064,000 5,893,000 13,064,000 6,401,000
Available-for-sale Securities [Member] | Equity Securities And Mutual Funds [Member]
         
Available-for-Sale Securities, Amortized cost Basis [Abstract]          
Available-for-Sale Securities, Cost Basis 38,683,000 33,561,000 38,683,000 33,561,000 29,181,000
Available-for-Sale Securities, Fair Value [Abstract]          
Available-for-Sale Securities, Fair Value 60,197,000 47,209,000 60,197,000 47,209,000 43,046,000
Available-for-Sale Securities, Gross Unrealized Gain (loss) [Abstract]          
Available-for-Sale Securities, Gross Unrealized Gain 21,513,000 14,170,000 21,513,000 14,170,000 14,192,000
Available-for-Sale Securities, Gross Unrealized Loss (2,000) (522,000) (2,000) (522,000) (327,000)
Available-for-Sale Securities, Other Than Temporary Impairment [Abstract]          
Available-for-Sale Securities, Other Than Temporary Impairment     0 0 0
Available-for-Sale Securities, Debt Maturities, Fair Value [Abstract]          
Available-for-Sale Securities 60,197,000 47,209,000 60,197,000 47,209,000 43,046,000
Available-for-Sale Securities, Temporarily Impaired Securities [Abstract]          
Available-for-Sale Securities, Temporarily impaired Securities, Number of Securities 1 3 1 3 2
Available-for-Sale Securities, Temporarily impaired Securities, Fair Value[Abstract]          
Available-for-Sale Securities, Temporarily impaired Securities, Less Than 12, Fair Value 213,000 2,681,000 213,000 2,681,000 0
Available-for-Sale Securities, Temporarily impaired Securities, 12 Months or longer, Fair Value 0 3,606,000 0 3,606,000 2,878,000
Available-for-Sale Securities, Temporarily impaired Securities, Total, Fair Value 213,000 6,287,000 213,000 6,287,000 2,878,000
Available-for-Sale Securities, Temporarily impaired Securities, Unrealized Loss [Abstract]          
Available-for-Sale Securities, Temporarily impaired Securities, Less Than 12,Unrealized Loss 2,000 523,000 2,000 523,000 0
Available-for-Sale Securities, Temporarily impaired Securities, 12 Months or longer, Unrealized Loss 0 132,000 0 132,000 327,000
Available-for-Sale Securities, Temporarily impaired Securities, Total, Unrealized Loss 2,000 655,000 2,000 655,000 327,000
Available-for-Sale Securities, Portfolio Concentration Ratings, Amortized Cost [Abstract]          
Available-for-Sale Securities, Portfolio Concentration Rated US Governement or GSE, Amortized Cost 0   0    
Available-for-Sale Securities, Portfolio Concentration Rated AAA to AA, Amortized Cost 0   0    
Available-for-Sale Securities, Portfolio Concentration Rated A to BBB, Amortized Cost 0   0    
Available-for-Sale Securities, Portfolio Concentration Rated Below Investment Grade, Amortized Cost 0   0    
Available-for-Sale Securities, Portfolio Concentration Not RatedAmortized Cost 38,683,000   38,683,000    
Available-for-Sale Securities, Portfolio Concentration Total, Amortized Cost 38,683,000 33,561,000 38,683,000 33,561,000 29,181,000
Available-for-Sale Securities, Portfolio Concentration Ratings, Fair Value [Abstract]          
Available-for-Sale Securities, Portfolio Concentration Rated US Governement or GSE, Fair Value 0   0    
Available-for-Sale Securities, Portfolio Concentration Rated AAA to AA, Fair Value 0   0    
Available-for-Sale Securities, Portfolio Concentration Rated A to BBB, Fair Value 0   0    
Available-for-Sale Securities, Portfolio Concentration Rated Below Investment Grade, Fair Value 0   0    
Available-for-Sale Securities, Portfolio Concentration Rated Not Rated Fair Value 60,197,000   60,197,000    
Available-for-Sale Securities, Fair Value 60,197,000 47,209,000 60,197,000 47,209,000 43,046,000
Available-for-sale Securities [Member] | Equity Securities Mutual Funds And Other Stock [Member]
         
Available-for-Sale Securities, Fair Value [Abstract]          
Available-for-Sale Securities, Fair Value 82,891,000   82,891,000    
Available-for-Sale Securities, Debt Maturities, Amortized Cost Basis [Abstract]          
Available-for-Sale Securities, Debt Maturities, Amortized Cost Basis 58,194,000   58,194,000    
Available-for-Sale Securities, Debt Maturities, Fair Value [Abstract]          
Available-for-Sale Securities 82,891,000   82,891,000    
Available-for-Sale Securities, Debt Maturities, Nominal Yield[Abstract]          
Available-for-Sale Securities, Debt Maturities, Nominal Yield     0.69    
Available-for-Sale Securities, Portfolio Concentration Ratings, Fair Value [Abstract]          
Available-for-Sale Securities, Fair Value 82,891,000   82,891,000    
Available-for-sale Securities [Member] | Perpetual Preferred Stock [Member]
         
Available-for-Sale Securities, Amortized cost Basis [Abstract]          
Available-for-Sale Securities, Cost Basis 19,511,000 19,224,000 19,511,000 19,224,000 19,511,000
Available-for-Sale Securities, Fair Value [Abstract]          
Available-for-Sale Securities, Fair Value 22,694,000 19,881,000 22,694,000 19,881,000 22,114,000
Available-for-Sale Securities, Gross Unrealized Gain (loss) [Abstract]          
Available-for-Sale Securities, Gross Unrealized Gain 3,183,000 790,000 3,183,000 790,000 2,603,000
Available-for-Sale Securities, Gross Unrealized Loss 0 (133,000) 0 (133,000) 0
Available-for-Sale Securities, Other Than Temporary Impairment [Abstract]          
Available-for-Sale Securities, Other Than Temporary Impairment     0 0 0
Available-for-Sale Securities, Debt Maturities, Fair Value [Abstract]          
Available-for-Sale Securities 22,694,000 19,881,000 22,694,000 19,881,000 22,114,000
Available-for-Sale Securities, Portfolio Concentration Ratings, Amortized Cost [Abstract]          
Available-for-Sale Securities, Portfolio Concentration Rated US Governement or GSE, Amortized Cost 0   0    
Available-for-Sale Securities, Portfolio Concentration Rated AAA to AA, Amortized Cost 0   0    
Available-for-Sale Securities, Portfolio Concentration Rated A to BBB, Amortized Cost 19,511,000   19,511,000    
Available-for-Sale Securities, Portfolio Concentration Rated Below Investment Grade, Amortized Cost 0   0    
Available-for-Sale Securities, Portfolio Concentration Not RatedAmortized Cost 0   0    
Available-for-Sale Securities, Portfolio Concentration Total, Amortized Cost 19,511,000 19,224,000 19,511,000 19,224,000 19,511,000
Available-for-Sale Securities, Portfolio Concentration Ratings, Fair Value [Abstract]          
Available-for-Sale Securities, Portfolio Concentration Rated US Governement or GSE, Fair Value 0   0    
Available-for-Sale Securities, Portfolio Concentration Rated AAA to AA, Fair Value 0   0    
Available-for-Sale Securities, Portfolio Concentration Rated A to BBB, Fair Value 22,694,000   22,694,000    
Available-for-Sale Securities, Portfolio Concentration Rated Below Investment Grade, Fair Value 0   0    
Available-for-Sale Securities, Portfolio Concentration Rated Not Rated Fair Value 0   0    
Available-for-Sale Securities, Fair Value 22,694,000 19,881,000 22,694,000 19,881,000 22,114,000
Available-for-sale Securities [Member] | Collateralized Mortgage Backed Securities [Member]
         
Available-for-Sale Securities, Fair Value [Abstract]          
Available-for-Sale Securities, Fair Value 9,407,011,000   9,407,011,000    
Available-for-Sale Securities, Debt Maturities, Amortized Cost Basis [Abstract]          
Available-for-Sale Securities, Debt Maturities, Amortized Cost Basis 9,170,211,000   9,170,211,000    
Available-for-Sale Securities, Debt Maturities, Fair Value [Abstract]          
Available-for-Sale Securities 9,407,011,000   9,407,011,000    
Available-for-Sale Securities, Debt Maturities, Nominal Yield[Abstract]          
Available-for-Sale Securities, Debt Maturities, Nominal Yield     3.79    
Available-for-Sale Securities, Portfolio Concentration Ratings, Fair Value [Abstract]          
Available-for-Sale Securities, Fair Value 9,407,011,000   9,407,011,000    
Held-to-maturity Securities [Member]
         
Available-for-Sale Securities, Amortized cost Basis [Abstract]          
Available-for-Sale Securities, Cost Basis 349,583,000   349,583,000    
Available-for-Sale Securities, Fair Value [Abstract]          
Available-for-Sale Securities, Fair Value 369,247,000   369,247,000    
Available-for-Sale Securities, Debt Maturities, Fair Value [Abstract]          
Available-for-Sale Securities 369,247,000   369,247,000    
Available-for-Sale Securities, Temporarily Impaired Securities [Abstract]          
Available-for-Sale Securities, Temporarily impaired Securities, Number of Securities         52
Available-for-Sale Securities, Temporarily impaired Securities, Fair Value[Abstract]          
Available-for-Sale Securities, Temporarily impaired Securities, Less Than 12, Fair Value         93,180,000
Available-for-Sale Securities, Temporarily impaired Securities, 12 Months or longer, Fair Value         786,000
Available-for-Sale Securities, Temporarily impaired Securities, Total, Fair Value         93,966,000
Available-for-Sale Securities, Temporarily impaired Securities, Unrealized Loss [Abstract]          
Available-for-Sale Securities, Temporarily impaired Securities, Less Than 12,Unrealized Loss         1,843,000
Available-for-Sale Securities, Temporarily impaired Securities, 12 Months or longer, Unrealized Loss         22,000
Available-for-Sale Securities, Temporarily impaired Securities, Total, Unrealized Loss         1,865,000
Available-for-Sale Securities, Portfolio Concentration Ratings, Amortized Cost [Abstract]          
Available-for-Sale Securities, Portfolio Concentration Rated US Governement or GSE, Amortized Cost 0   0    
Available-for-Sale Securities, Portfolio Concentration Rated AAA to AA, Amortized Cost 238,357,000   238,357,000    
Available-for-Sale Securities, Portfolio Concentration Rated A to BBB, Amortized Cost 31,248,000   31,248,000    
Available-for-Sale Securities, Portfolio Concentration Rated Below Investment Grade, Amortized Cost 0   0    
Available-for-Sale Securities, Portfolio Concentration Not RatedAmortized Cost 79,978,000   79,978,000    
Available-for-Sale Securities, Portfolio Concentration Total, Amortized Cost 349,583,000   349,583,000    
Available-for-Sale Securities, Portfolio Concentration Ratings, Fair Value [Abstract]          
Available-for-Sale Securities, Portfolio Concentration Rated US Governement or GSE, Fair Value 0   0    
Available-for-Sale Securities, Portfolio Concentration Rated AAA to AA, Fair Value 255,075,000   255,075,000    
Available-for-Sale Securities, Portfolio Concentration Rated A to BBB, Fair Value 32,029,000   32,029,000    
Available-for-Sale Securities, Portfolio Concentration Rated Below Investment Grade, Fair Value 0   0    
Available-for-Sale Securities, Portfolio Concentration Rated Not Rated Fair Value 82,143,000   82,143,000    
Available-for-Sale Securities, Fair Value 369,247,000   369,247,000    
Held-to-maturity Securities [Member] | Municipal And Other Tax Exempt Securities [Member]
         
Available-for-Sale Securities, Amortized cost Basis [Abstract]          
Available-for-Sale Securities, Cost Basis 160,870,000   160,870,000    
Available-for-Sale Securities, Fair Value [Abstract]          
Available-for-Sale Securities, Fair Value 165,449,000   165,449,000    
Available-for-Sale Securities, Debt Maturities, Fair Value [Abstract]          
Available-for-Sale Securities 165,449,000   165,449,000    
Available-for-Sale Securities, Temporarily Impaired Securities [Abstract]          
Available-for-Sale Securities, Temporarily impaired Securities, Number of Securities 2 13 2 13 37
Available-for-Sale Securities, Temporarily impaired Securities, Fair Value[Abstract]          
Available-for-Sale Securities, Temporarily impaired Securities, Less Than 12, Fair Value 619,000 5,606,000 619,000 5,606,000 12,482,000
Available-for-Sale Securities, Temporarily impaired Securities, 12 Months or longer, Fair Value 0 1,437,000 0 1,437,000 786,000
Available-for-Sale Securities, Temporarily impaired Securities, Total, Fair Value 619,000 7,043,000 619,000 7,043,000 13,268,000
Available-for-Sale Securities, Temporarily impaired Securities, Unrealized Loss [Abstract]          
Available-for-Sale Securities, Temporarily impaired Securities, Less Than 12,Unrealized Loss 4,000 31,000 4,000 31,000 211,000
Available-for-Sale Securities, Temporarily impaired Securities, 12 Months or longer, Unrealized Loss 0 10,000 0 10,000 22,000
Available-for-Sale Securities, Temporarily impaired Securities, Total, Unrealized Loss 4,000 41,000 4,000 41,000 233,000
Available-for-Sale Securities, Portfolio Concentration Ratings, Amortized Cost [Abstract]          
Available-for-Sale Securities, Portfolio Concentration Rated US Governement or GSE, Amortized Cost 0   0    
Available-for-Sale Securities, Portfolio Concentration Rated AAA to AA, Amortized Cost 58,023,000   58,023,000    
Available-for-Sale Securities, Portfolio Concentration Rated A to BBB, Amortized Cost 29,898,000   29,898,000    
Available-for-Sale Securities, Portfolio Concentration Rated Below Investment Grade, Amortized Cost 0   0    
Available-for-Sale Securities, Portfolio Concentration Not RatedAmortized Cost 72,949,000   72,949,000    
Available-for-Sale Securities, Portfolio Concentration Total, Amortized Cost 160,870,000   160,870,000    
Available-for-Sale Securities, Portfolio Concentration Ratings, Fair Value [Abstract]          
Available-for-Sale Securities, Portfolio Concentration Rated US Governement or GSE, Fair Value 0   0    
Available-for-Sale Securities, Portfolio Concentration Rated AAA to AA, Fair Value 59,743,000   59,743,000    
Available-for-Sale Securities, Portfolio Concentration Rated A to BBB, Fair Value 30,679,000   30,679,000    
Available-for-Sale Securities, Portfolio Concentration Rated Below Investment Grade, Fair Value 0   0    
Available-for-Sale Securities, Portfolio Concentration Rated Not Rated Fair Value 75,027,000   75,027,000    
Available-for-Sale Securities, Fair Value 165,449,000   165,449,000    
Held-to-maturity Securities [Member] | Other Debt Obligations [Member]
         
Available-for-Sale Securities, Amortized cost Basis [Abstract]          
Available-for-Sale Securities, Cost Basis 160,870,000   160,870,000    
Available-for-Sale Securities, Fair Value [Abstract]          
Available-for-Sale Securities, Fair Value 203,798,000   203,798,000    
Available-for-Sale Securities, Debt Maturities, Fair Value [Abstract]          
Available-for-Sale Securities 203,798,000   203,798,000    
Available-for-Sale Securities, Temporarily Impaired Securities [Abstract]          
Available-for-Sale Securities, Temporarily impaired Securities, Number of Securities 0 1 0 1 15
Available-for-Sale Securities, Temporarily impaired Securities, Fair Value[Abstract]          
Available-for-Sale Securities, Temporarily impaired Securities, Less Than 12, Fair Value 0 14,215,000 0 14,215,000 80,698,000
Available-for-Sale Securities, Temporarily impaired Securities, 12 Months or longer, Fair Value 0 0 0 0 0
Available-for-Sale Securities, Temporarily impaired Securities, Total, Fair Value 0 14,215,000 0 14,215,000 80,698,000
Available-for-Sale Securities, Temporarily impaired Securities, Unrealized Loss [Abstract]          
Available-for-Sale Securities, Temporarily impaired Securities, Less Than 12,Unrealized Loss 0 235,000 0 235,000 1,632,000
Available-for-Sale Securities, Temporarily impaired Securities, 12 Months or longer, Unrealized Loss 0 0 0 0 0
Available-for-Sale Securities, Temporarily impaired Securities, Total, Unrealized Loss 0 235,000 0 235,000 1,632,000
Available-for-Sale Securities, Portfolio Concentration Ratings, Amortized Cost [Abstract]          
Available-for-Sale Securities, Portfolio Concentration Rated US Governement or GSE, Amortized Cost 0   0    
Available-for-Sale Securities, Portfolio Concentration Rated AAA to AA, Amortized Cost 180,334,000   180,334,000    
Available-for-Sale Securities, Portfolio Concentration Rated A to BBB, Amortized Cost 1,350,000   1,350,000    
Available-for-Sale Securities, Portfolio Concentration Rated Below Investment Grade, Amortized Cost 0   0    
Available-for-Sale Securities, Portfolio Concentration Not RatedAmortized Cost 72,949,000   72,949,000    
Available-for-Sale Securities, Portfolio Concentration Total, Amortized Cost 160,870,000   160,870,000    
Available-for-Sale Securities, Portfolio Concentration Ratings, Fair Value [Abstract]          
Available-for-Sale Securities, Portfolio Concentration Rated US Governement or GSE, Fair Value 0   0    
Available-for-Sale Securities, Portfolio Concentration Rated AAA to AA, Fair Value 195,332,000   195,332,000    
Available-for-Sale Securities, Portfolio Concentration Rated A to BBB, Fair Value 1,350,000   1,350,000    
Available-for-Sale Securities, Portfolio Concentration Rated Below Investment Grade, Fair Value 0   0    
Available-for-Sale Securities, Portfolio Concentration Rated Not Rated Fair Value 7,116,000   7,116,000    
Available-for-Sale Securities, Fair Value 203,798,000   203,798,000    
Available For Sale And Investment Securities [Member]
         
Available-for-Sale Securities, Temporarily Impaired Securities [Abstract]          
Available-for-Sale Securities, Temporarily impaired Securities, Number of Securities 124 130 124 130 212
Available-for-Sale Securities, Temporarily impaired Securities, Fair Value[Abstract]          
Available-for-Sale Securities, Temporarily impaired Securities, Less Than 12, Fair Value 354,015,000 272,310,000 354,015,000 272,310,000 1,712,618,000
Available-for-Sale Securities, Temporarily impaired Securities, 12 Months or longer, Fair Value 478,779,000 662,343,000 478,779,000 662,343,000 633,491,000
Available-for-Sale Securities, Temporarily impaired Securities, Total, Fair Value 832,794,000 934,653,000 832,794,000 934,653,000 2,346,109,000
Available-for-Sale Securities, Temporarily impaired Securities, Unrealized Loss [Abstract]          
Available-for-Sale Securities, Temporarily impaired Securities, Less Than 12,Unrealized Loss 2,134,000 7,040,000 2,134,000 7,040,000 23,512,000
Available-for-Sale Securities, Temporarily impaired Securities, 12 Months or longer, Unrealized Loss 69,013,000 115,635,000 69,013,000 115,635,000 71,742,000
Available-for-Sale Securities, Temporarily impaired Securities, Total, Unrealized Loss 71,147,000 122,675,000 71,147,000 122,675,000 93,254,000
Unrealized loss remains in OCI after an other-than-temporary credit loss has been recognized in income [Member] | Municipal And Other Tax Exempt Securities [Member]
         
Available-for-Sale Securities, Temporarily Impaired Securities [Abstract]          
Available-for-Sale Securities, Temporarily impaired Securities, Number of Securities 21   21   11
Available-for-Sale Securities, Temporarily impaired Securities, Fair Value[Abstract]          
Available-for-Sale Securities, Temporarily impaired Securities, Less Than 12, Fair Value 6,948,000   6,948,000   10,713,000
Available-for-Sale Securities, Temporarily impaired Securities, 12 Months or longer, Fair Value 7,115,000   7,115,000   0
Available-for-Sale Securities, Temporarily impaired Securities, Total, Fair Value 14,063,000   14,063,000   10,713,000
Available-for-Sale Securities, Temporarily impaired Securities, Unrealized Loss [Abstract]          
Available-for-Sale Securities, Temporarily impaired Securities, Less Than 12,Unrealized Loss 244,000   244,000   105,000
Available-for-Sale Securities, Temporarily impaired Securities, 12 Months or longer, Unrealized Loss 277,000   277,000   0
Available-for-Sale Securities, Temporarily impaired Securities, Total, Unrealized Loss 521,000   521,000   105,000
Unrealized loss remains in OCI after an other-than-temporary credit loss has been recognized in income [Member] | Alt A [Member]
         
Available-for-Sale Securities, Temporarily Impaired Securities [Abstract]          
Available-for-Sale Securities, Temporarily impaired Securities, Number of Securities 19 16 19 16 19
Available-for-Sale Securities, Temporarily impaired Securities, Fair Value[Abstract]          
Available-for-Sale Securities, Temporarily impaired Securities, Less Than 12, Fair Value 0 0 0 0 0
Available-for-Sale Securities, Temporarily impaired Securities, 12 Months or longer, Fair Value 153,632,000 153,012,000 153,632,000 153,012,000 172,153,000
Available-for-Sale Securities, Temporarily impaired Securities, Total, Fair Value 153,632,000 153,012,000 153,632,000 153,012,000 172,153,000
Available-for-Sale Securities, Temporarily impaired Securities, Unrealized Loss [Abstract]          
Available-for-Sale Securities, Temporarily impaired Securities, Less Than 12,Unrealized Loss 0 0 0 0 0
Available-for-Sale Securities, Temporarily impaired Securities, 12 Months or longer, Unrealized Loss 29,117,000 52,219,000 29,117,000 52,219,000 33,305,000
Available-for-Sale Securities, Temporarily impaired Securities, Total, Unrealized Loss 29,117,000 52,219,000 29,117,000 52,219,000 33,305,000
Unrealized loss remains in OCI after an other-than-temporary credit loss has been recognized in income [Member] | Jumbo A Loans [Member]
         
Available-for-Sale Securities, Temporarily Impaired Securities [Abstract]          
Available-for-Sale Securities, Temporarily impaired Securities, Number of Securities 21 25 21 25 25
Available-for-Sale Securities, Temporarily impaired Securities, Fair Value[Abstract]          
Available-for-Sale Securities, Temporarily impaired Securities, Less Than 12, Fair Value 0 0 0 0 0
Available-for-Sale Securities, Temporarily impaired Securities, 12 Months or longer, Fair Value 138,205,000 160,872,000 138,205,000 160,872,000 166,401,000
Available-for-Sale Securities, Temporarily impaired Securities, Total, Fair Value 138,205,000 160,872,000 138,205,000 160,872,000 166,401,000
Available-for-Sale Securities, Temporarily impaired Securities, Unrealized Loss [Abstract]          
Available-for-Sale Securities, Temporarily impaired Securities, Less Than 12,Unrealized Loss 0 0 0 0 0
Available-for-Sale Securities, Temporarily impaired Securities, 12 Months or longer, Unrealized Loss 27,470,000 34,259,000 27,470,000 34,259,000 23,419,000
Available-for-Sale Securities, Temporarily impaired Securities, Total, Unrealized Loss 27,470,000 34,259,000 27,470,000 34,259,000 23,419,000
Municipal And Other Tax Exempt Securities [Member]
         
Trading Securities [Abstract]          
Amortized Cost 160,870,000 221,702,000 160,870,000 221,702,000 184,898,000
Investments securities, fair value 165,449,000 227,301,000 165,449,000 227,301,000 188,577,000
Not Recognized in OCI Gross Unrealized Gain 4,583,000 [1] 5,640,000 [1] 4,583,000 [1] 5,640,000 [1] 3,912,000 [1]
Not Recognized in OCI Gross Unrealized Loss (4,000) [1] (41,000) [1] (4,000) [1] (41,000) [1] (233,000) [1]
Held-to-Maturity,Amortized Cost [Abstract]          
Held-to-Maturity,Amortized Cost,Less Than One Year 49,599,000   49,599,000    
Held-to-Maturity,Amortized Cost,One to Five Years 81,448,000   81,448,000    
Held-to-Maturity,Amortized Cost,Six to Ten Years 24,506,000   24,506,000    
Held-to-Maturity,Amortized Cost,Over Ten Year 5,317,000   5,317,000    
Held-to-Maturity,Amortized Cost,Total 160,870,000 221,702,000 160,870,000 221,702,000 184,898,000
Held-to-Maturity,Amortized Cost,Weighted Average Maturity (in years) 2.82 [2]   2.82 [2]    
Held-to-Maturity,Fair Value [Abstract]          
Held-to-Maturity,Fair Value,Less Than One Year 49,937,000   49,937,000    
Held-to-Maturity,Fair Value,One to Five Years 84,499,000   84,499,000    
Held-to-Maturity,Fair Value,Six to Ten Years 25,547,000   25,547,000    
Held-to-Maturity,Fair Value,Over Ten Year 5,466,000   5,466,000    
Held-to-Maturity,Fair Value,Total 165,449,000 227,301,000 165,449,000 227,301,000 188,577,000
Held-to-Maturity,Nominal Yield (in hundredths) [Abstract]          
Held-to-Maturity,Less Than One Year,Nominal Yield (in hundredths)     4.64 [3]    
Held-to-Maturity,One to Five Years,Nominal Yield (in hundredths)     4.66 [3]    
Held-to-Maturity,Six to Ten Years,Nominal Yield (in hundredths)     5.58 [3]    
Held-to-Maturity,Over Ten Year,Nominal Yield (in hundredths)     6.22 [3]    
Held-to-Maturity,Nominal Yield (in hundredths)     4.84 [3]    
Effective tax rate     39.00%    
Other Debt Obligations [Member]
         
Trading Securities [Abstract]          
Amortized Cost 188,713,000 131,575,000 188,713,000 131,575,000 154,655,000
Investments securities, fair value 203,798,000 136,585,000 203,798,000 136,585,000 157,528,000
Not Recognized in OCI Gross Unrealized Gain 15,085,000 [1] 5,245,000 [1] 15,085,000 [1] 5,245,000 [1] 4,505,000 [1]
Not Recognized in OCI Gross Unrealized Loss 0 [1] (235,000) [1] 0 [1] (235,000) [1] (1,632,000) [1]
Held-to-Maturity,Amortized Cost [Abstract]          
Held-to-Maturity,Amortized Cost,Less Than One Year 7,729,000   7,729,000    
Held-to-Maturity,Amortized Cost,One to Five Years 29,513,000   29,513,000    
Held-to-Maturity,Amortized Cost,Six to Ten Years 34,784,000   34,784,000    
Held-to-Maturity,Amortized Cost,Over Ten Year 116,687,000   116,687,000    
Held-to-Maturity,Amortized Cost,Total 188,713,000 131,575,000 188,713,000 131,575,000 154,655,000
Held-to-Maturity,Amortized Cost,Weighted Average Maturity (in years) 10.50 [2]   10.50 [2]    
Held-to-Maturity,Fair Value [Abstract]          
Held-to-Maturity,Fair Value,Less Than One Year 7,764,000   7,764,000    
Held-to-Maturity,Fair Value,One to Five Years 30,203,000   30,203,000    
Held-to-Maturity,Fair Value,Six to Ten Years 36,286,000   36,286,000    
Held-to-Maturity,Fair Value,Over Ten Year 129,545,000   129,545,000    
Held-to-Maturity,Fair Value,Total 203,798,000 136,585,000 203,798,000 136,585,000 157,528,000
Held-to-Maturity,Nominal Yield (in hundredths) [Abstract]          
Held-to-Maturity,Less Than One Year,Nominal Yield (in hundredths)     4.52    
Held-to-Maturity,One to Five Years,Nominal Yield (in hundredths)     5.44    
Held-to-Maturity,Six to Ten Years,Nominal Yield (in hundredths)     5.58    
Held-to-Maturity,Over Ten Year,Nominal Yield (in hundredths)     6.20    
Held-to-Maturity,Nominal Yield (in hundredths)     5.90    
Municipal And Other Tax-Exempt And Other Debt Securities [Member]
         
Available-for-Sale Securities, Fair Value [Abstract]          
Available-for-Sale Securities, Fair Value 77,106,000   77,106,000    
Available-for-Sale Securities, Debt Maturities, Amortized Cost Basis [Abstract]          
Available-for-Sale Securities, Debt Maturities, Less Than One Year 1,745,000   1,745,000    
Available-for-Sale Securities, Debt Maturities, One to Five Years 6,941,000   6,941,000    
Available-for-Sale Securities, Debt Maturities, Six to Ten Years 12,575,000   12,575,000    
Available-for-Sale Securities, Debt Maturities, Over Ten Years 54,142,000   54,142,000    
Available-for-Sale Securities, Debt Maturities, Amortized Cost Basis 75,403,000   75,403,000    
Available-for-Sale Securities, Debt Maturities, Fair Value [Abstract]          
Available-for-Sale Securities, Debt Maturities, Less Than One Year, Fair Value 1,755,000   1,755,000    
Available-for-Sale Securities, Debt Maturities, One to Five YearsFair Value 8,077,000   8,077,000    
Available-for-Sale Securities, Debt Maturities, Six to Ten YearsFair Value 13,678,000   13,678,000    
Available-for-Sale Securities, Debt Maturities, Over Ten YearsFair Value 53,596,000   53,596,000    
Available-for-Sale Securities 77,106,000   77,106,000    
Available-for-Sale Securities, Debt Maturities, Amortized Cost Basis Weighted Average Maturity 20.51   20.51    
Available-for-Sale Securities, Debt Maturities, Nominal Yield[Abstract]          
Available-for-Sale Securities, Debt Maturities, Less Than One YearNominal Yield     3.3    
Available-for-Sale Securities, Debt Maturities, One to Five Years Nominal Yield     3.67    
Available-for-Sale Securities, Debt Maturities, Six to Ten Years Nominal Yield     4.08    
Available-for-Sale Securities, Debt Maturities, Over Ten Years Nominal Yield     1.03    
Available-for-Sale Securities, Debt Maturities, Nominal Yield     1.84    
Available-for-Sale Securities, Portfolio Concentration Ratings, Fair Value [Abstract]          
Available-for-Sale Securities, Fair Value 77,106,000   77,106,000    
Loan To Value Below 70 Percent [Member]
         
Distribution of Amortized Cost and Fair Value For Below Investment Grade Residential Mortgage-Backed Securities [Abstract]          
Number of Securities 5   5    
Amortized Cost 28,550,000   28,550,000    
Fair Value 26,598,000   26,598,000    
Credit losses Recognized [Abstract]          
Number of Securites in Current Period 0        
Amount of Credit Losses Recognized in Currrent Period 0        
Number of Securites in Life-to-Date 0   0    
Amount of Credit Losses Recognized in Life-to-Date 0        
Loan To Value From 70 To 75 Percent [Member]
         
Distribution of Amortized Cost and Fair Value For Below Investment Grade Residential Mortgage-Backed Securities [Abstract]          
Number of Securities 0   0    
Amortized Cost 0   0    
Fair Value 0   0    
Credit losses Recognized [Abstract]          
Number of Securites in Current Period 0        
Amount of Credit Losses Recognized in Currrent Period 0        
Number of Securites in Life-to-Date 0   0    
Amount of Credit Losses Recognized in Life-to-Date 0        
Loan To Value From 75 To 80 Percent [Member]
         
Distribution of Amortized Cost and Fair Value For Below Investment Grade Residential Mortgage-Backed Securities [Abstract]          
Number of Securities 3   3    
Amortized Cost 38,159,000   38,159,000    
Fair Value 35,453,000   35,453,000    
Credit losses Recognized [Abstract]          
Number of Securites in Current Period 0        
Amount of Credit Losses Recognized in Currrent Period 0        
Number of Securites in Life-to-Date 0   0    
Amount of Credit Losses Recognized in Life-to-Date 0        
Loan To Value From 80 To 85 [Member]
         
Distribution of Amortized Cost and Fair Value For Below Investment Grade Residential Mortgage-Backed Securities [Abstract]          
Number of Securities 2   2    
Amortized Cost 29,636,000   29,636,000    
Fair Value 26,927,000   26,927,000    
Credit losses Recognized [Abstract]          
Number of Securites in Current Period 1        
Amount of Credit Losses Recognized in Currrent Period 255,000        
Number of Securites in Life-to-Date 1   1    
Amount of Credit Losses Recognized in Life-to-Date 3,603,000        
Loan To Value Equal To Or Greater Than 85 Percent [Member]
         
Distribution of Amortized Cost and Fair Value For Below Investment Grade Residential Mortgage-Backed Securities [Abstract]          
Number of Securities 50   50    
Amortized Cost 373,051,000   373,051,000    
Fair Value 318,343,000   318,343,000    
Credit losses Recognized [Abstract]          
Number of Securites in Current Period 33        
Amount of Credit Losses Recognized in Currrent Period 4,048,000        
Number of Securites in Life-to-Date 43   43    
Amount of Credit Losses Recognized in Life-to-Date $ 56,904,000        
[1] Other Comprehensive income
[2] Expected maturities may differ from contractual maturities, because borrowers may have the right to call or prepay obligations with or without penalty.
[3] Calculated on a taxable equivalent basis using a 39% effective tax rate