Securities (Details 4) (USD $)	Dec. 31, 2013	Dec. 31, 2012
Securities available-for-sale:
Securities available-for-sale, Fair Value, Less than 12 months	$ 2,708,675,000	$ 1,940,958,000
Securities available-for-sale, Estimated Unrealized Loss, Less than 12 months	44,276,000	6,543,000
Securities available-for-sale, Fair Value, 12 months or greater	784,342,000	55,943,000
Securities available-for-sale, Estimated Unrealized Loss, 12 months or greater	38,365,000	8,001,000
Securities available-for-sale, Fair Value, Total	3,493,017,000	1,996,901,000
Securities available-for-sale, Estimated Unrealized Loss, Total	82,641,000	14,544,000
Securities held-to-maturity:
Securities held-to-maturity, Fair Value, Less than 12 months	2,462,226,000	156,856,000
Securities held-to-maturity, Estimated Unrealized Loss, Less than 12 months	66,879,000	1,421,000
Securities held-to-maturity, Fair Value, 12 months or greater	119,716,000
Securities held-to-maturity, Estimated Unrealized Loss, 12 months or greater	10,427,000
Securities held-to-maturity, Fair Value, Total	2,581,942,000	156,856,000
Securities held-to-maturity, Estimated Unrealized Loss, Total	77,306,000	1,421,000
Other information
Fair value securities, having non-credit impairment recognized in AOCI	2,580,000,000	16,200,000
Temporarily impaired securities	3,490,000,000	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
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	1,026,142,000	346,136,000
Securities available-for-sale, Estimated Unrealized Loss, Less than 12 months	7,911,000	203,000
Securities available-for-sale, Fair Value, Total	1,026,142,000	346,136,000
Securities available-for-sale, Estimated Unrealized Loss, Total	7,911,000	203,000
Securities held-to-maturity:
Securities held-to-maturity, Fair Value, Less than 12 months	156,290,000
Securities held-to-maturity, Estimated Unrealized Loss, Less than 12 months	5,122,000
Securities held-to-maturity, Fair Value, Total	156,290,000
Securities held-to-maturity, Estimated Unrealized Loss, Total	5,122,000
Other information
Number of available-for-sale and held-to-maturity securities in the unrealized loss position	47	8
Federal agency - MBS
Securities available-for-sale:
Securities available-for-sale, Fair Value, Less than 12 months	17,962,000	50,932,000
Securities available-for-sale, Estimated Unrealized Loss, Less than 12 months	85,000	69,000
Securities available-for-sale, Fair Value, 12 months or greater	43,492,000	46,000
Securities available-for-sale, Estimated Unrealized Loss, 12 months or greater	2,703,000
Securities available-for-sale, Fair Value, Total	61,454,000	50,978,000
Securities available-for-sale, Estimated Unrealized Loss, Total	2,788,000	69,000
Securities held-to-maturity:
Securities held-to-maturity, Fair Value, Less than 12 months	321,090,000	31,514,000
Securities held-to-maturity, Estimated Unrealized Loss, Less than 12 months	10,513,000	182,000
Securities held-to-maturity, Fair Value, 12 months or greater	15,338,000
Securities held-to-maturity, Estimated Unrealized Loss, 12 months or greater	1,417,000
Securities held-to-maturity, Fair Value, Total	336,428,000	31,514,000
Securities held-to-maturity, Estimated Unrealized Loss, Total	11,930,000	182,000
Other information
Number of available-for-sale and held-to-maturity securities in the unrealized loss position	44	7
CMOs - Federal agency
Securities available-for-sale:
Securities available-for-sale, Fair Value, Less than 12 months	1,637,994,000	1,413,367,000
Securities available-for-sale, Estimated Unrealized Loss, Less than 12 months	35,922,000	5,994,000
Securities available-for-sale, Fair Value, 12 months or greater	728,101,000	13,565,000
Securities available-for-sale, Estimated Unrealized Loss, 12 months or greater	34,849,000	44,000
Securities available-for-sale, Fair Value, Total	2,366,095,000	1,426,932,000
Securities available-for-sale, Estimated Unrealized Loss, Total	70,771,000	6,038,000
Securities held-to-maturity:
Securities held-to-maturity, Fair Value, Less than 12 months	1,539,464,000	60,998,000
Securities held-to-maturity, Estimated Unrealized Loss, Less than 12 months	36,435,000	382,000
Securities held-to-maturity, Fair Value, 12 months or greater	63,276,000
Securities held-to-maturity, Estimated Unrealized Loss, 12 months or greater	4,186,000
Securities held-to-maturity, Fair Value, Total	1,602,740,000	60,998,000
Securities held-to-maturity, Estimated Unrealized Loss, Total	40,621,000	382,000
Other information
Number of available-for-sale and held-to-maturity securities in the unrealized loss position	182	53
CMOs - Non-agency
Securities available-for-sale:
Securities available-for-sale, Fair Value, Less than 12 months	10,056,000
Securities available-for-sale, Estimated Unrealized Loss, Less than 12 months	319,000
Securities available-for-sale, Fair Value, 12 months or greater	8,483,000	25,484,000
Securities available-for-sale, Estimated Unrealized Loss, 12 months or greater	729,000	2,124,000
Securities available-for-sale, Fair Value, Total	18,539,000	25,484,000
Securities available-for-sale, Estimated Unrealized Loss, Total	1,048,000	2,124,000
Other information
Number of available-for-sale and held-to-maturity securities in the unrealized loss position	4	4
State and municipal
Securities available-for-sale:
Securities available-for-sale, Fair Value, Less than 12 months	16,521,000	85,550,000
Securities available-for-sale, Estimated Unrealized Loss, Less than 12 months	39,000	225,000
Securities available-for-sale, Fair Value, 12 months or greater	4,266,000	810,000
Securities available-for-sale, Estimated Unrealized Loss, 12 months or greater	84,000	14,000
Securities available-for-sale, Fair Value, Total	20,787,000	86,360,000
Securities available-for-sale, Estimated Unrealized Loss, Total	123,000	239,000
Securities held-to-maturity:
Securities held-to-maturity, Fair Value, Less than 12 months	347,305,000	64,344,000
Securities held-to-maturity, Estimated Unrealized Loss, Less than 12 months	14,190,000	857,000
Securities held-to-maturity, Fair Value, 12 months or greater	41,102,000
Securities held-to-maturity, Estimated Unrealized Loss, 12 months or greater	4,824,000
Securities held-to-maturity, Fair Value, Total	388,407,000	64,344,000
Securities held-to-maturity, Estimated Unrealized Loss, Total	19,014,000	857,000
Other information
Number of available-for-sale and held-to-maturity securities in the unrealized loss position	520	152
Other debt securities
Securities available-for-sale:
Securities available-for-sale, Fair Value, Less than 12 months		39,877,000
Securities available-for-sale, Estimated Unrealized Loss, Less than 12 months		49,000
Securities available-for-sale, Fair Value, 12 months or greater		16,038,000
Securities available-for-sale, Estimated Unrealized Loss, 12 months or greater		5,819,000
Securities available-for-sale, Fair Value, Total		55,915,000
Securities available-for-sale, Estimated Unrealized Loss, Total		5,868,000
Securities held-to-maturity:
Securities held-to-maturity, Fair Value, Less than 12 months	98,077,000
Securities held-to-maturity, Estimated Unrealized Loss, Less than 12 months	619,000
Securities held-to-maturity, Fair Value, Total	98,077,000
Securities held-to-maturity, Estimated Unrealized Loss, Total	$ 619,000
Other information
Number of available-for-sale and held-to-maturity securities in the unrealized loss position	12	5
Total debt securities
Other information
Number of available-for-sale and held-to-maturity securities in the unrealized loss position	809	231