Investment (Held-to-Maturity) Securities (Details) (USD $)	3 Months Ended
	Jun. 30, 2014		Dec. 31, 2013		Jun. 30, 2013		Sep. 30, 2011
Schedule of Investment (Held-to-Maturity) Securities [Line Items]
Investment Securities, Amortized Cost	$ 648,843,000		$ 676,047,000		$ 612,770,000
Investments Securities, Carrying Value	649,937,000	[1]	677,878,000	[2]	615,790,000	[3]
Investment securities, fair value	670,811,000		687,127,000		625,705,000
Investment Securities, Gross Unrealized Gain	21,559,000	[4]	12,687,000	[4]	15,791,000	[4]
Investment Securities, Gross Unrealized Loss	(685,000)	[4]	(3,438,000)	[4]	(5,876,000)	[4]
Investment Securities, Debt Maturities, Net Carrying Value [Abstract]
Investment Securities, Debt Maturities, Net Carrying Value	649,937,000	[1]	677,878,000	[2]	615,790,000	[3]
Investment Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]
Investment Securities, Debt Maturities, Fair value	670,811,000		687,127,000		625,705,000
Investment Securities, Debt Maturities, Nominal Yield [Abstract]
Investment Securities, Debt Maturities, Nominal Yield	3.17%
Investment Securities, Pledged as Collateral [Abstract]
Investment Securities, Pledged as Collateral, Carrying Value	77,835,000		89,087,000		97,286,000
Investment Securities, Pledged as Collateral, Fair Value	81,248,000		91,804,000		100,644,000
Investment Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Investment Securities, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	72		139		163
Investment Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Investment Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	3,593,000		192,538,000		272,738,000
Investment Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	105,767,000		53,850,000		0
Investment Securities, Continuous Unrealized Loss Position, Fair Value	109,360,000		246,388,000		272,738,000
Investment Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Investment Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	40,000		2,526,000		5,876,000
Investment Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	645,000		912,000		0
Investment Securities, Continuous Unrealized Loss Position, Accumulated Loss	685,000		3,438,000		5,876,000
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	41,973,000	[5]
Investment Securities, Portfolio Concentration US Govt or GSE Securities Not Rated, Fair Value	44,176,000	[5]
Investment Securities, Portfolio Concentration Rated AAA to AA, Carrying Value	431,851,000
Investment Securities, Portfolio Concentration Rated AAA to AA, Fair Value	447,315,000
Investment Securities, Portfolio Concentration Rated A to BBB, Carrying Value	16,497,000
Investment Securities, Portfolio Concentration Rated A to BBB, Fair Value	16,721,000
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	159,616,000
Investment Securities, Portfolio Concentration Not Rated, Fair Value	162,599,000
Fixed Maturity Securities [Member]
Schedule of Investment (Held-to-Maturity) Securities [Line Items]
Investments Securities, Carrying Value	607,964,000
Investment securities, fair value	626,635,000
Investment Securities, Debt Maturities, Net Carrying Value [Abstract]
Investment Securities, Debt Maturities, Less than One Year, Net Carrying Value	49,815,000
Investment Securities, Debt Maturities, One to Five Years, Net Carrying Value	329,761,000
Investment Securities, Debt Maturities, Six to Ten Years, Net Carrying Value	99,904,000
Investment Securities, Debt Maturities, Over Ten Years, Net Carrying Value	128,484,000
Investment Securities, Debt Maturities, Net Carrying Value	607,964,000
Investment Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]
Investment Securities, Debt Maturities, Less Than One Year, Fair Value	50,045,000
Investment Securities, Debt Maturities, One to Five Years, Fair Value	332,282,000
Investment Securities, Debt Maturities, Six to Ten Years, Fair Value	102,780,000
Investment Securities, Debt Maturities, Over Ten Years, Fair Value	141,528,000
Investment Securities, Debt Maturities, Fair value	626,635,000
Investment Securities, Debt Maturities, Nominal Yield [Abstract]
Investment Securities, Debt Maturities, Less Than One Year, Nominal Yield	2.39%
Investment Securities, Debt Maturities, One to Five Years, Nominal Yield	2.01%
Investment Securities, Debt Maturities, Six to Ten Years, Nominal Yield	3.94%
Investment Securities, Debt Maturities, Over Ten Years, Nominal Yield	6.02%
Investment Securities, Debt Maturities, Nominal Yield	3.20%
Investment Securities, Debt Maturities, Weighted Average Maturity	5.39	[6]
Municipal and other tax-exempt securities [Member]
Schedule of Investment (Held-to-Maturity) Securities [Line Items]
Investment Securities, Amortized Cost	425,221,000		440,187,000		375,317,000
Investments Securities, Carrying Value	425,221,000	[1]	440,187,000	[2]	375,317,000	[3]
Investment securities, fair value	429,051,000		439,870,000		371,690,000
Investment Securities, Gross Unrealized Gain	4,442,000	[4]	2,452,000	[4]	2,189,000	[4]
Investment Securities, Gross Unrealized Loss	(612,000)	[4]	(2,769,000)	[4]	(5,816,000)	[4]
Investment Securities, Debt Maturities, Net Carrying Value [Abstract]
Investment Securities, Debt Maturities, Less than One Year, Net Carrying Value	36,962,000
Investment Securities, Debt Maturities, One to Five Years, Net Carrying Value	296,908,000
Investment Securities, Debt Maturities, Six to Ten Years, Net Carrying Value	52,328,000
Investment Securities, Debt Maturities, Over Ten Years, Net Carrying Value	39,023,000
Investment Securities, Debt Maturities, Net Carrying Value	425,221,000	[1]	440,187,000	[2]	375,317,000	[3]
Investment Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]
Investment Securities, Debt Maturities, Less Than One Year, Fair Value	37,136,000
Investment Securities, Debt Maturities, One to Five Years, Fair Value	298,655,000
Investment Securities, Debt Maturities, Six to Ten Years, Fair Value	52,567,000
Investment Securities, Debt Maturities, Over Ten Years, Fair Value	40,693,000
Investment Securities, Debt Maturities, Fair value	429,051,000		439,870,000		371,690,000
Investment Securities, Debt Maturities, Nominal Yield [Abstract]
Investment Securities, Debt Maturities, Less Than One Year, Nominal Yield	1.99%	[7]
Investment Securities, Debt Maturities, One to Five Years, Nominal Yield	1.70%	[7]
Investment Securities, Debt Maturities, Six to Ten Years, Nominal Yield	2.64%	[7]
Investment Securities, Debt Maturities, Over Ten Years, Nominal Yield	5.35%	[7]
Investment Securities, Debt Maturities, Nominal Yield	2.18%	[7]
Investment Securities, Debt Maturities, Weighted Average Maturity	4.14	[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	42		107		149
Investment Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Investment Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	0		166,382,000		271,897,000
Investment Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	104,959,000		53,073,000		0
Investment Securities, Continuous Unrealized Loss Position, Fair Value	104,959,000		219,455,000		271,897,000
Investment Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Investment Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	0		1,921,000		5,816,000
Investment Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	612,000		848,000		0
Investment Securities, Continuous Unrealized Loss Position, Accumulated Loss	612,000		2,769,000		5,816,000
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	271,498,000
Investment Securities, Portfolio Concentration Rated AAA to AA, Fair Value	272,244,000
Investment Securities, Portfolio Concentration Rated A to BBB, Carrying Value	16,497,000
Investment Securities, Portfolio Concentration Rated A to BBB, Fair Value	16,721,000
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	137,226,000
Investment Securities, Portfolio Concentration Not Rated, Fair Value	140,086,000
Other debt securities [Member]
Schedule of Investment (Held-to-Maturity) Securities [Line Items]
Investment Securities, Amortized Cost	182,743,000		187,509,000		176,301,000
Investments Securities, Carrying Value	182,743,000	[1]	187,509,000	[2]	176,301,000	[3]
Investment securities, fair value	197,584,000		195,393,000		187,219,000
Investment Securities, Gross Unrealized Gain	14,914,000	[4]	8,497,000	[4]	10,978,000	[4]
Investment Securities, Gross Unrealized Loss	(73,000)	[4]	(613,000)	[4]	(60,000)	[4]
Investment Securities, Debt Maturities, Net Carrying Value [Abstract]
Investment Securities, Debt Maturities, Less than One Year, Net Carrying Value	12,853,000
Investment Securities, Debt Maturities, One to Five Years, Net Carrying Value	32,853,000
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	182,743,000	[1]	187,509,000	[2]	176,301,000	[3]
Investment Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]
Investment Securities, Debt Maturities, Less Than One Year, Fair Value	12,909,000
Investment Securities, Debt Maturities, One to Five Years, Fair Value	33,627,000
Investment Securities, Debt Maturities, Six to Ten Years, Fair Value	50,213,000
Investment Securities, Debt Maturities, Over Ten Years, Fair Value	100,835,000
Investment Securities, Debt Maturities, Fair value	197,584,000		195,393,000		187,219,000
Investment Securities, Debt Maturities, Nominal Yield [Abstract]
Investment Securities, Debt Maturities, Less Than One Year, Nominal Yield	3.54%
Investment Securities, Debt Maturities, One to Five Years, Nominal Yield	4.78%
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	8.32	[6]
Investment Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Investment Securities, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	30		30		14
Investment Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Investment Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	3,593,000		10,932,000		841,000
Investment Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	808,000		777,000		0
Investment Securities, Continuous Unrealized Loss Position, Fair Value	4,401,000		11,709,000		841,000
Investment Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Investment Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	40,000		549,000		60,000
Investment Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	33,000		64,000		0
Investment Securities, Continuous Unrealized Loss Position, Accumulated Loss	73,000		613,000		60,000
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	175,071,000
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	22,390,000
Investment Securities, Portfolio Concentration Not Rated, Fair Value	22,513,000
U.S. agency residential mortgage-backed securities [Member] | Other [Member]
Schedule of Investment (Held-to-Maturity) Securities [Line Items]
Investment Securities, Amortized Cost	40,879,000		48,351,000		61,152,000
Investments Securities, Carrying Value	41,973,000	[1]	50,182,000	[2]	64,172,000	[3]
Investment securities, fair value	44,176,000		51,864,000		66,796,000
Investment Securities, Gross Unrealized Gain	2,203,000	[4]	1,738,000	[4]	2,624,000	[4]
Investment Securities, Gross Unrealized Loss	0	[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	1,100,000		1,800,000		3,000,000		13,000,000
Investment Securities, Debt Maturities, Net Carrying Value [Abstract]
Investment Securities, Debt Maturities, Net Carrying Value	41,973,000	[1]	50,182,000	[2]	64,172,000	[3]
Investment Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]
Investment Securities, Debt Maturities, Fair value	44,176,000		51,864,000		66,796,000
Investment Securities, Debt Maturities, Nominal Yield [Abstract]
Investment Securities, Debt Maturities, Nominal Yield	2.74%	[8]
Investment Securities, Debt Maturities, Average Expected Life of Mortgage-backed Securities	2 years 11 months
Investment Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Investment Securities, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	0		2		0
Investment Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Investment Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	0		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	0		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	0		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	0		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	41,973,000	[5]
Investment Securities, Portfolio Concentration US Govt or GSE Securities Not Rated, Fair Value	44,176,000	[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 $1.1 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 $3.0 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.