Securities (Details 4) (USD $)	Sep. 30, 2013	Dec. 31, 2012
Securities available-for-sale:
Securities available-for-sale, Fair Value, Less than 12 months	$ 3,655,789,000	$ 1,940,958,000
Securities available-for-sale, Estimated Unrealized Loss, Less than 12 months	79,709,000	6,543,000
Securities available-for-sale, Fair Value, 12 months or greater	166,609,000	55,943,000
Securities available-for-sale, Estimated Unrealized Loss, 12 months or greater	8,700,000	8,001,000
Securities available-for-sale, Fair Value, Total	3,822,398,000	1,996,901,000
Securities available-for-sale, Estimated Unrealized Loss, Total	88,409,000	14,544,000
Securities held-to-maturity
Securities held-to-maturity, Fair Value, Less than 12 months	1,173,032,000	156,856,000
Securities held-to-maturity, Estimated Unrealized Loss, Less than 12 months	47,042,000	1,421,000
Securities held-to-maturity, Fair Value, Total	1,173,032,000	156,856,000
Securities held-to-maturity, Estimated Unrealized Loss, Total	47,042,000	1,421,000
Gross Unrealized Losses	47,042,000	1,421,000
Securities available-for-sale:
Gross Unrealized Losses	88,409,000	14,544,000
Other information
Fair value securities, having non-credit impairment recognized in AOCI		16,200,000
Temporarily impaired securities		1,980,000,000
U.S. Treasury
Securities available-for-sale:
Securities available-for-sale, Fair Value, Less than 12 months		5,096,000
Securities available-for-sale, Estimated Unrealized Loss, Less than 12 months		3,000
Securities available-for-sale, Fair Value, Total		5,096,000
Securities available-for-sale, Estimated Unrealized Loss, Total		3,000
Securities available-for-sale:
Gross Unrealized Losses		3,000
Other information
Number of available-for-sale and held-to-maturity securities in the unrealized loss position		2
Federal agency - Debt
Securities available-for-sale:
Securities available-for-sale, Fair Value, Less than 12 months	611,954,000	346,136,000
Securities available-for-sale, Estimated Unrealized Loss, Less than 12 months	5,650,000	203,000
Securities available-for-sale, Fair Value, Total	611,954,000	346,136,000
Securities available-for-sale, Estimated Unrealized Loss, Total	5,650,000	203,000
Securities held-to-maturity
Securities held-to-maturity, Fair Value, Less than 12 months	128,715,000
Securities held-to-maturity, Estimated Unrealized Loss, Less than 12 months	4,305,000
Securities held-to-maturity, Fair Value, Total	128,715,000
Securities held-to-maturity, Estimated Unrealized Loss, Total	4,305,000
Gross Unrealized Losses	4,305,000
Securities available-for-sale:
Gross Unrealized Losses	5,650,000	203,000
Other information
Number of available-for-sale and held-to-maturity securities in the unrealized loss position	32	8
Federal agency - MBS
Securities available-for-sale:
Securities available-for-sale, Fair Value, Less than 12 months	45,176,000	50,932,000
Securities available-for-sale, Estimated Unrealized Loss, Less than 12 months	2,226,000	69,000
Securities available-for-sale, Fair Value, 12 months or greater	45,000	46,000
Securities available-for-sale, Fair Value, Total	45,221,000	50,978,000
Securities available-for-sale, Estimated Unrealized Loss, Total	2,226,000	69,000
Securities held-to-maturity
Securities held-to-maturity, Fair Value, Less than 12 months	231,160,000	31,514,000
Securities held-to-maturity, Estimated Unrealized Loss, Less than 12 months	9,753,000	182,000
Securities held-to-maturity, Fair Value, Total	231,160,000	31,514,000
Securities held-to-maturity, Estimated Unrealized Loss, Total	9,753,000	182,000
Gross Unrealized Losses	9,753,000	182,000
Securities available-for-sale:
Gross Unrealized Losses	2,226,000	69,000
Other information
Number of available-for-sale and held-to-maturity securities in the unrealized loss position	26	7
CMOs - Federal agency
Securities available-for-sale:
Securities available-for-sale, Fair Value, Less than 12 months	2,774,796,000	1,413,367,000
Securities available-for-sale, Estimated Unrealized Loss, Less than 12 months	69,757,000	5,994,000
Securities available-for-sale, Fair Value, 12 months or greater	96,544,000	13,565,000
Securities available-for-sale, Estimated Unrealized Loss, 12 months or greater	1,813,000	44,000
Securities available-for-sale, Fair Value, Total	2,871,340,000	1,426,932,000
Securities available-for-sale, Estimated Unrealized Loss, Total	71,570,000	6,038,000
Securities held-to-maturity
Securities held-to-maturity, Fair Value, Less than 12 months	583,595,000	60,998,000
Securities held-to-maturity, Estimated Unrealized Loss, Less than 12 months	18,158,000	382,000
Securities held-to-maturity, Fair Value, Total	583,595,000	60,998,000
Securities held-to-maturity, Estimated Unrealized Loss, Total	18,158,000	382,000
Gross Unrealized Losses	18,158,000	382,000
Securities available-for-sale:
Gross Unrealized Losses	71,570,000	6,038,000
Other information
Number of available-for-sale and held-to-maturity securities in the unrealized loss position	161	53
CMOs - Non-agency
Securities available-for-sale:
Securities available-for-sale, Fair Value, Less than 12 months	14,620,000
Securities available-for-sale, Estimated Unrealized Loss, Less than 12 months	517,000
Securities available-for-sale, Fair Value, 12 months or greater	8,432,000	25,484,000
Securities available-for-sale, Estimated Unrealized Loss, 12 months or greater	868,000	2,124,000
Securities available-for-sale, Fair Value, Total	23,052,000	25,484,000
Securities available-for-sale, Estimated Unrealized Loss, Total	1,385,000	2,124,000
Securities available-for-sale:
Gross Unrealized Losses	1,385,000	2,124,000
Other information
Number of available-for-sale and held-to-maturity securities in the unrealized loss position	6	4
State and municipal
Securities available-for-sale:
Securities available-for-sale, Fair Value, Less than 12 months	90,545,000	85,550,000
Securities available-for-sale, Estimated Unrealized Loss, Less than 12 months	328,000	225,000
Securities available-for-sale, Fair Value, 12 months or greater	46,216,000	810,000
Securities available-for-sale, Estimated Unrealized Loss, 12 months or greater	1,009,000	14,000
Securities available-for-sale, Fair Value, Total	136,761,000	86,360,000
Securities available-for-sale, Estimated Unrealized Loss, Total	1,337,000	239,000
Securities held-to-maturity
Securities held-to-maturity, Fair Value, Less than 12 months	229,562,000	64,344,000
Securities held-to-maturity, Estimated Unrealized Loss, Less than 12 months	14,826,000	857,000
Securities held-to-maturity, Fair Value, Total	229,562,000	64,344,000
Securities held-to-maturity, Estimated Unrealized Loss, Total	14,826,000	857,000
Gross Unrealized Losses	14,826,000	857,000
Securities available-for-sale:
Gross Unrealized Losses	1,337,000	239,000
Other information
Number of available-for-sale and held-to-maturity securities in the unrealized loss position	454	152
Other debt securities
Securities available-for-sale:
Securities available-for-sale, Fair Value, Less than 12 months	118,698,000	39,877,000
Securities available-for-sale, Estimated Unrealized Loss, Less than 12 months	1,231,000	49,000
Securities available-for-sale, Fair Value, 12 months or greater	15,372,000	16,038,000
Securities available-for-sale, Estimated Unrealized Loss, 12 months or greater	5,010,000	5,819,000
Securities available-for-sale, Fair Value, Total	134,070,000	55,915,000
Securities available-for-sale, Estimated Unrealized Loss, Total	6,241,000	5,868,000
Securities held-to-maturity
Number of highly rated corporate debt and collateralized bond obligations	1
Securities available-for-sale:
Gross Unrealized Losses	6,241,000	5,868,000
Other information
Number of available-for-sale and held-to-maturity securities in the unrealized loss position	9	5
Total debt securities
Securities available-for-sale:
Gross Unrealized Losses	88,409,000	14,544,000
Other information
Number of available-for-sale and held-to-maturity securities in the unrealized loss position	688	231
Collateralized debt obligations
Securities available-for-sale:
Gross Unrealized Losses	$ 5,000,000