Investment (Held-to-Maturity) Securities (Details) (USD $)	Mar. 31, 2014		Dec. 31, 2013		Mar. 31, 2013		Sep. 30, 2011
Schedule of Investment (Held-to-Maturity) Securities [Line Items]
Investment Securities, Amortized Cost	$ 667,548,000		$ 676,047,000		$ 585,378,000
Investments Securities, Carrying Value	668,976,000	[1]	677,878,000	[2]	589,271,000	[3]
Investment securities, fair value	685,063,000		687,127,000		615,194,000
Investment Securities, Gross Unrealized Gain	18,253,000	[4]	12,687,000	[4]	26,554,000	[4]
Investment Securities, Gross Unrealized Loss	(2,166,000)	[4]	(3,438,000)	[4]	(631,000)	[4]
Investment Securities, Debt Maturities, Net Carrying Value [Abstract]
Investment Securities, Debt Maturities, Net Carrying Value	668,976,000	[1]	677,878,000	[2]	589,271,000	[3]
Investment Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]
Investment Securities, Debt Maturities, Fair value	685,063,000		687,127,000		615,194,000
Investment Securities, Debt Maturities, Nominal Yield [Abstract]
Investment Securities, Debt Maturities, Nominal Yield	3.20%
Investment Securities, Pledged as Collateral [Abstract]
Investment Securities, Pledged as Collateral, Carrying Value	87,757,000		89,087,000		112,990,000
Investment Securities, Pledged as Collateral, Fair Value	90,765,000		91,804,000		118,054,000
Investment Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Investment Securities, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	128		139		77
Investment Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Investment Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	100,994,000		192,538,000		142,630,000
Investment Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	118,707,000		53,850,000		0
Investment Securities, Continuous Unrealized Loss Position, Fair Value	219,701,000		246,388,000		142,630,000
Investment Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Investment Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	771,000		2,526,000		631,000
Investment Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	1,395,000		912,000		0
Investment Securities, Continuous Unrealized Loss Position, Accumulated Loss	2,166,000		3,438,000		631,000
Other than Temporary Impairment Losses, Investment Securities, Portion Recognized in Earnings, Net, Qualitative Disclosures, Lowest Current Credit Rating [Abstract]
Investment Securities, Portfolio Concentration US Govt or GSE Securities Not Rated, Carrying Value	45,917,000	[5]
Investment Securities, Portfolio Concentration US Govt or GSE Securities Not Rated, Fair Value	47,834,000	[5]
Investment Securities, Portfolio Concentration Rated AAA to AA, Carrying Value	440,861,000
Investment Securities, Portfolio Concentration Rated AAA to AA, Fair Value	452,875,000
Investment Securities, Portfolio Concentration Rated A to BBB, Carrying Value	18,107,000
Investment Securities, Portfolio Concentration Rated A to BBB, Fair Value	18,298,000
Investment Securities, Portfolio Concentration Rated Below Investment Grade, Carrying Value	0
Investment Securities, Portfolio Concentration Rated Below Investment Grade, Fair Value	0
Investment Securities, Portfolio Concentration Not Rated, Carrying Value	164,091,000
Investment Securities, Portfolio Concentration Not Rated, Fair Value	166,056,000
Fixed Maturity Securities [Member]
Schedule of Investment (Held-to-Maturity) Securities [Line Items]
Investments Securities, Carrying Value	623,059,000
Investment securities, fair value	637,229,000
Investment Securities, Debt Maturities, Net Carrying Value [Abstract]
Investment Securities, Debt Maturities, Less than One Year, Net Carrying Value	53,346,000
Investment Securities, Debt Maturities, One to Five Years, Net Carrying Value	343,378,000
Investment Securities, Debt Maturities, Six to Ten Years, Net Carrying Value	97,694,000
Investment Securities, Debt Maturities, Over Ten Years, Net Carrying Value	128,641,000
Investment Securities, Debt Maturities, Net Carrying Value	623,059,000
Investment Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]
Investment Securities, Debt Maturities, Less Than One Year, Fair Value	53,515,000
Investment Securities, Debt Maturities, One to Five Years, Fair Value	344,264,000
Investment Securities, Debt Maturities, Six to Ten Years, Fair Value	99,594,000
Investment Securities, Debt Maturities, Over Ten Years, Fair Value	139,856,000
Investment Securities, Debt Maturities, Fair value	637,229,000
Investment Securities, Debt Maturities, Nominal Yield [Abstract]
Investment Securities, Debt Maturities, Less Than One Year, Nominal Yield	2.81%
Investment Securities, Debt Maturities, One to Five Years, Nominal Yield	2.01%
Investment Securities, Debt Maturities, Six to Ten Years, Nominal Yield	4.11%
Investment Securities, Debt Maturities, Over Ten Years, Nominal Yield	6.02%
Investment Securities, Debt Maturities, Nominal Yield	3.24%
Investment Securities, Debt Maturities, Weighted Average Maturity	5.48	[6]
Municipal and other tax-exempt securities [Member]
Schedule of Investment (Held-to-Maturity) Securities [Line Items]
Investment Securities, Amortized Cost	440,303,000		440,187,000		339,003,000
Investments Securities, Carrying Value	440,303,000	[1]	440,187,000	[2]	339,003,000	[3]
Investment securities, fair value	441,532,000		439,870,000		341,940,000
Investment Securities, Gross Unrealized Gain	3,182,000	[4]	2,452,000	[4]	3,518,000	[4]
Investment Securities, Gross Unrealized Loss	(1,953,000)	[4]	(2,769,000)	[4]	(581,000)	[4]
Investment Securities, Debt Maturities, Net Carrying Value [Abstract]
Investment Securities, Debt Maturities, Less than One Year, Net Carrying Value	39,986,000
Investment Securities, Debt Maturities, One to Five Years, Net Carrying Value	311,019,000
Investment Securities, Debt Maturities, Six to Ten Years, Net Carrying Value	50,118,000
Investment Securities, Debt Maturities, Over Ten Years, Net Carrying Value	39,180,000
Investment Securities, Debt Maturities, Net Carrying Value	440,303,000	[1]	440,187,000	[2]	339,003,000	[3]
Investment Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]
Investment Securities, Debt Maturities, Less Than One Year, Fair Value	40,099,000
Investment Securities, Debt Maturities, One to Five Years, Fair Value	311,262,000
Investment Securities, Debt Maturities, Six to Ten Years, Fair Value	49,968,000
Investment Securities, Debt Maturities, Over Ten Years, Fair Value	40,203,000
Investment Securities, Debt Maturities, Fair value	441,532,000		439,870,000		341,940,000
Investment Securities, Debt Maturities, Nominal Yield [Abstract]
Investment Securities, Debt Maturities, Less Than One Year, Nominal Yield	2.61%	[7]
Investment Securities, Debt Maturities, One to Five Years, Nominal Yield	1.72%	[7]
Investment Securities, Debt Maturities, Six to Ten Years, Nominal Yield	2.91%	[7]
Investment Securities, Debt Maturities, Over Ten Years, Nominal Yield	5.35%	[7]
Investment Securities, Debt Maturities, Nominal Yield	2.26%	[7]
Investment Securities, Debt Maturities, Weighted Average Maturity	4.21	[6]
Investment Securities,Debt Maturities, Effective tax rate for nominal yield calculation	39.00%
Investment Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Investment Securities, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	96		107		63
Investment Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Investment Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	78,833,000		166,382,000		141,778,000
Investment Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	117,909,000		53,073,000		0
Investment Securities, Continuous Unrealized Loss Position, Fair Value	196,742,000		219,455,000		141,778,000
Investment Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Investment Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	601,000		1,921,000		581,000
Investment Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	1,352,000		848,000		0
Investment Securities, Continuous Unrealized Loss Position, Accumulated Loss	1,953,000		2,769,000		581,000
Other than Temporary Impairment Losses, Investment Securities, Portion Recognized in Earnings, Net, Qualitative Disclosures, Lowest Current Credit Rating [Abstract]
Investment Securities, Portfolio Concentration US Govt or GSE Securities Not Rated, Carrying Value	0	[5]
Investment Securities, Portfolio Concentration US Govt or GSE Securities Not Rated, Fair Value	0	[5]
Investment Securities, Portfolio Concentration Rated AAA to AA, Carrying Value	280,508,000
Investment Securities, Portfolio Concentration Rated AAA to AA, Fair Value	279,497,000
Investment Securities, Portfolio Concentration Rated A to BBB, Carrying Value	18,107,000
Investment Securities, Portfolio Concentration Rated A to BBB, Fair Value	18,298,000
Investment Securities, Portfolio Concentration Rated Below Investment Grade, Carrying Value	0
Investment Securities, Portfolio Concentration Rated Below Investment Grade, Fair Value	0
Investment Securities, Portfolio Concentration Not Rated, Carrying Value	141,688,000
Investment Securities, Portfolio Concentration Not Rated, Fair Value	143,737,000
Other debt securities [Member]
Schedule of Investment (Held-to-Maturity) Securities [Line Items]
Investment Securities, Amortized Cost	182,756,000		187,509,000		177,300,000
Investments Securities, Carrying Value	182,756,000	[1]	187,509,000	[2]	177,300,000	[3]
Investment securities, fair value	195,697,000		195,393,000		196,403,000
Investment Securities, Gross Unrealized Gain	13,114,000	[4]	8,497,000	[4]	19,153,000	[4]
Investment Securities, Gross Unrealized Loss	(173,000)	[4]	(613,000)	[4]	(50,000)	[4]
Investment Securities, Debt Maturities, Net Carrying Value [Abstract]
Investment Securities, Debt Maturities, Less than One Year, Net Carrying Value	13,360,000
Investment Securities, Debt Maturities, One to Five Years, Net Carrying Value	32,359,000
Investment Securities, Debt Maturities, Six to Ten Years, Net Carrying Value	47,576,000
Investment Securities, Debt Maturities, Over Ten Years, Net Carrying Value	89,461,000
Investment Securities, Debt Maturities, Net Carrying Value	182,756,000	[1]	187,509,000	[2]	177,300,000	[3]
Investment Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]
Investment Securities, Debt Maturities, Less Than One Year, Fair Value	13,416,000
Investment Securities, Debt Maturities, One to Five Years, Fair Value	33,002,000
Investment Securities, Debt Maturities, Six to Ten Years, Fair Value	49,626,000
Investment Securities, Debt Maturities, Over Ten Years, Fair Value	99,653,000
Investment Securities, Debt Maturities, Fair value	195,697,000		195,393,000		196,403,000
Investment Securities, Debt Maturities, Nominal Yield [Abstract]
Investment Securities, Debt Maturities, Less Than One Year, Nominal Yield	3.41%
Investment Securities, Debt Maturities, One to Five Years, Nominal Yield	4.85%
Investment Securities, Debt Maturities, Six to Ten Years, Nominal Yield	5.37%
Investment Securities, Debt Maturities, Over Ten Years, Nominal Yield	6.32%
Investment Securities, Debt Maturities, Nominal Yield	5.60%
Investment Securities, Debt Maturities, Weighted Average Maturity	8.56	[6]
Investment Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Investment Securities, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	31		30		14
Investment Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Investment Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	12,516,000		10,932,000		852,000
Investment Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	798,000		777,000		0
Investment Securities, Continuous Unrealized Loss Position, Fair Value	13,314,000		11,709,000		852,000
Investment Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Investment Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	130,000		549,000		50,000
Investment Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	43,000		64,000		0
Investment Securities, Continuous Unrealized Loss Position, Accumulated Loss	173,000		613,000		50,000
Other than Temporary Impairment Losses, Investment Securities, Portion Recognized in Earnings, Net, Qualitative Disclosures, Lowest Current Credit Rating [Abstract]
Investment Securities, Portfolio Concentration US Govt or GSE Securities Not Rated, Carrying Value	0	[5]
Investment Securities, Portfolio Concentration US Govt or GSE Securities Not Rated, Fair Value	0	[5]
Investment Securities, Portfolio Concentration Rated AAA to AA, Carrying Value	160,353,000
Investment Securities, Portfolio Concentration Rated AAA to AA, Fair Value	173,378,000
Investment Securities, Portfolio Concentration Rated A to BBB, Carrying Value	0
Investment Securities, Portfolio Concentration Rated A to BBB, Fair Value	0
Investment Securities, Portfolio Concentration Rated Below Investment Grade, Carrying Value	0
Investment Securities, Portfolio Concentration Rated Below Investment Grade, Fair Value	0
Investment Securities, Portfolio Concentration Not Rated, Carrying Value	22,403,000
Investment Securities, Portfolio Concentration Not Rated, Fair Value	22,319,000
U.S. agency residential mortgage-backed securities [Member] | Other [Member]
Schedule of Investment (Held-to-Maturity) Securities [Line Items]
Investment Securities, Amortized Cost	44,489,000		48,351,000		69,075,000
Investments Securities, Carrying Value	45,917,000	[1]	50,182,000	[2]	72,968,000	[3]
Investment securities, fair value	47,834,000		51,864,000		76,851,000
Investment Securities, Gross Unrealized Gain	1,957,000	[4]	1,738,000	[4]	3,883,000	[4]
Investment Securities, Gross Unrealized Loss	(40,000)	[4]	(56,000)	[4]	0	[4]
Investments Securities, Transfers [Abstract]
Investment Securities, Transferred From Available For Sale Securities Portfolio, Fair Value							131,000,000
Investment Securities, Transferred From Available For Sale Securities Portfolio, Amortized Cost							118,000,000
Investment Securities, Transferred From Available For Sale Securities Portfolio, Net Unrealized Gain	1,400,000		1,800,000		3,900,000		13,000,000
Investment Securities, Debt Maturities, Net Carrying Value [Abstract]
Investment Securities, Debt Maturities, Net Carrying Value	45,917,000	[1]	50,182,000	[2]	72,968,000	[3]
Investment Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]
Investment Securities, Debt Maturities, Fair value	47,834,000		51,864,000		76,851,000
Investment Securities, Debt Maturities, Nominal Yield [Abstract]
Investment Securities, Debt Maturities, Nominal Yield	2.73%	[8]
Investment Securities, Debt Maturities, Average Expected Life of Mortgage-backed Securities	3 years
Investment Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Investment Securities, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	1		2		0
Investment Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Investment Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	9,645,000		15,224,000		0
Investment Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	0		0		0
Investment Securities, Continuous Unrealized Loss Position, Fair Value	9,645,000		15,224,000		0
Investment Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Investment Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	40,000		56,000		0
Investment Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0		0		0
Investment Securities, Continuous Unrealized Loss Position, Accumulated Loss	40,000		56,000		0
Other than Temporary Impairment Losses, Investment Securities, Portion Recognized in Earnings, Net, Qualitative Disclosures, Lowest Current Credit Rating [Abstract]
Investment Securities, Portfolio Concentration US Govt or GSE Securities Not Rated, Carrying Value	45,917,000	[5]
Investment Securities, Portfolio Concentration US Govt or GSE Securities Not Rated, Fair Value	47,834,000	[5]
Investment Securities, Portfolio Concentration Rated AAA to AA, Carrying Value	0
Investment Securities, Portfolio Concentration Rated AAA to AA, Fair Value	0
Investment Securities, Portfolio Concentration Rated A to BBB, Carrying Value	0
Investment Securities, Portfolio Concentration Rated A to BBB, Fair Value	0
Investment Securities, Portfolio Concentration Rated Below Investment Grade, Carrying Value	0
Investment Securities, Portfolio Concentration Rated Below Investment Grade, Fair Value	0
Investment Securities, Portfolio Concentration Not Rated, Carrying Value	0
Investment Securities, Portfolio Concentration Not Rated, Fair Value	$ 0

[1] Carrying value includes $1.4 million of net unrealized gain which remains in Accumulated other comprehensive income (“AOCI”) in the Consolidated Balance Sheets related to certain securities transferred from the Available for Sale securities portfolio to the Investment securities portfolio as discussed in greater detail following.

[2] Carrying value includes $1.8 million of net unrealized gain which remains in Accumulated other comprehensive income (“AOCI”) in the Consolidated Balance Sheets related to certain securities transferred from the Available for Sale securities portfolio to the Investment securities portfolio as discussed in greater detail following.

[3] Carrying value includes $3.9 million of net unrealized gain which remains in Accumulated other comprehensive income (“AOCI”) in the Consolidated Balance Sheets related to certain securities transferred from the Available for Sale securities portfolio to the Investment securities portfolio as discussed in greater detail following.

[4] Gross unrealized gains and losses are not recognized in AOCI in the Consolidated Balance Sheets.

[5] U.S. government and government sponsored enterprises are not rated by the nationally-recognized rating agencies as these securities are guaranteed by agencies of the U.S. government or government-sponsored enterprises.

[6] Expected maturities may differ from contractual maturities, because borrowers may have the right to call or prepay obligations with or without penalty.

[7] Calculated on a taxable equivalent basis using a 39% effective tax rate.

[8] The nominal yield on residential mortgage-backed securities is based upon prepayment assumptions at the purchase date. Actual yields earned may differ significantly based upon actual prepayments. See Quarterly Financial Summary - Unaudited for current yields on the investment securities portfolio.