Securities (Details 4) (USD $)	Jun. 30, 2012	Dec. 31, 2011
Securities available-for-sale:
Securities available-for-sale, Fair Value, Less than 12 months	$ 504,039,000	$ 1,278,941,000
Securities available-for-sale, Estimated Unrealized Loss, Less than 12 months	963,000	4,221,000
Securities available-for-sale, Fair Value, 12 months or greater	50,926,000	48,141,000
Securities available-for-sale, Estimated Unrealized Loss, 12 months or greater	13,272,000	18,957,000
Securities available-for-sale, Fair Value, Total	554,965,000	1,327,082,000
Securities available-for-sale, Estimated Unrealized Loss, Total	14,235,000	23,178,000
Securities held-to-maturity:
Securities held-to-maturity, Fair Value, Less than 12 months	81,927,000	38,040,000
Securities held-to-maturity, Estimated Unrealized Loss, Less than 12 months	1,330,000	232,000
Securities held-to-maturity, Fair Value, Total	81,927,000	38,040,000
Securities held-to-maturity, Estimated Unrealized Loss, Total	1,330,000	232,000
Other information
Fair value securities, having non-credit impairment recognized in AOCI	19,300,000	9,200,000
Temporarily impaired securities	535,700,000	1,320,000,000
U.S. Treasury
Securities available-for-sale:
Securities available-for-sale, Fair Value, Less than 12 months	12,206,000	4,145,000
Securities available-for-sale, Estimated Unrealized Loss, Less than 12 months	16,000	5,000
Securities available-for-sale, Fair Value, Total	12,206,000	4,145,000
Securities available-for-sale, Estimated Unrealized Loss, Total	16,000	5,000
Other information
Number of available-for-sale and held-to-maturity securities in the unrealized loss position	4	2
Federal agency - Debt
Securities available-for-sale:
Securities available-for-sale, Fair Value, Less than 12 months	54,606,000	409,129,000
Securities available-for-sale, Estimated Unrealized Loss, Less than 12 months	15,000	296,000
Securities available-for-sale, Fair Value, Total	54,606,000	409,129,000
Securities available-for-sale, Estimated Unrealized Loss, Total	15,000	296,000
Other information
Number of available-for-sale and held-to-maturity securities in the unrealized loss position	2	12
Federal agency - MBS
Securities available-for-sale:
Securities available-for-sale, Fair Value, Less than 12 months		24,519,000
Securities available-for-sale, Estimated Unrealized Loss, Less than 12 months		87,000
Securities available-for-sale, Fair Value, Total		24,519,000
Securities available-for-sale, Estimated Unrealized Loss, Total		87,000
Securities held-to-maturity:
Securities held-to-maturity, Fair Value, Less than 12 months	9,852,000
Securities held-to-maturity, Estimated Unrealized Loss, Less than 12 months	99,000
Securities held-to-maturity, Fair Value, Total	9,852,000
Securities held-to-maturity, Estimated Unrealized Loss, Total	99,000
Other information
Number of available-for-sale and held-to-maturity securities in the unrealized loss position	1	3
CMOs - Federal agency
Securities available-for-sale:
Securities available-for-sale, Fair Value, Less than 12 months	416,059,000	744,737,000
Securities available-for-sale, Estimated Unrealized Loss, Less than 12 months	850,000	2,224,000
Securities available-for-sale, Fair Value, Total	416,059,000	744,737,000
Securities available-for-sale, Estimated Unrealized Loss, Total	850,000	2,224,000
Securities held-to-maturity:
Securities held-to-maturity, Fair Value, Less than 12 months	5,121,000	32,256,000
Securities held-to-maturity, Estimated Unrealized Loss, Less than 12 months	22,000	195,000
Securities held-to-maturity, Fair Value, Total	5,121,000	32,256,000
Securities held-to-maturity, Estimated Unrealized Loss, Total	22,000	195,000
Other information
Number of available-for-sale and held-to-maturity securities in the unrealized loss position	20	36
CMOs - Non-agency
Securities available-for-sale:
Securities available-for-sale, Fair Value, Less than 12 months	3,918,000	20,094,000
Securities available-for-sale, Estimated Unrealized Loss, Less than 12 months	19,000	833,000
Securities available-for-sale, Fair Value, 12 months or greater	33,743,000	31,400,000
Securities available-for-sale, Estimated Unrealized Loss, 12 months or greater	6,056,000	10,487,000
Securities available-for-sale, Fair Value, Total	37,661,000	51,494,000
Securities available-for-sale, Estimated Unrealized Loss, Total	6,075,000	11,320,000
Other information
Number of available-for-sale and held-to-maturity securities in the unrealized loss position	7	12
State and municipal
Securities available-for-sale:
Securities available-for-sale, Fair Value, Less than 12 months	4,006,000	42,164,000
Securities available-for-sale, Estimated Unrealized Loss, Less than 12 months	60,000	268,000
Securities available-for-sale, Fair Value, 12 months or greater	1,415,000	2,023,000
Securities available-for-sale, Estimated Unrealized Loss, 12 months or greater	41,000	105,000
Securities available-for-sale, Fair Value, Total	5,421,000	44,187,000
Securities available-for-sale, Estimated Unrealized Loss, Total	101,000	373,000
Securities held-to-maturity:
Securities held-to-maturity, Fair Value, Less than 12 months	66,954,000	5,784,000
Securities held-to-maturity, Estimated Unrealized Loss, Less than 12 months	1,209,000	37,000
Securities held-to-maturity, Fair Value, Total	66,954,000	5,784,000
Securities held-to-maturity, Estimated Unrealized Loss, Total	1,209,000	37,000
Other information
Number of available-for-sale and held-to-maturity securities in the unrealized loss position	105	19
Other debt securities
Securities available-for-sale:
Securities available-for-sale, Fair Value, Less than 12 months	13,244,000	34,153,000
Securities available-for-sale, Estimated Unrealized Loss, Less than 12 months	3,000	508,000
Securities available-for-sale, Fair Value, 12 months or greater	15,768,000	14,718,000
Securities available-for-sale, Estimated Unrealized Loss, 12 months or greater	7,175,000	8,365,000
Securities available-for-sale, Fair Value, Total	29,012,000	48,871,000
Securities available-for-sale, Estimated Unrealized Loss, Total	7,178,000	8,873,000
Other information
Number of available-for-sale and held-to-maturity securities in the unrealized loss position	2	6
Collateralized debt obligations
Securities available-for-sale:
Securities available-for-sale, Estimated Unrealized Loss, Total	$ 7,000,000
Total debt securities
Other information
Number of available-for-sale and held-to-maturity securities in the unrealized loss position	141	90