Securities (Details 2) (USD $)	Dec. 31, 2013	Dec. 31, 2012
Expected remaining maturities of debt securities available-for-sale, fair value
Fair Value	$ 6,241,117,000	$ 9,205,989,000
Expected remaining maturities of debt securities held-to-maturity, amortized cost
Total of debt securities held-to-maturity, amortized cost	2,957,843,000	1,398,403,000
Securities pledged to secure trust funds, public deposits, or for other purposes required or permitted by law	1,180,000,000
Securities pledged with right by contract or custom to sell or repledge	12,376,000	48,697,000
Total debt securities
Expected remaining maturities of debt securities available-for-sale, fair value
Securities available-for-sale, One year or less, fair value	666,619,000
Securities available-for-sale, Over 1 year through 5 years, fair value	5,004,391,000
Securities available-for-sale, Over 5 years through 10 years, fair value	558,328,000
Securities available-for-sale, Over 10 years, fair value	3,336,000
Fair Value	6,232,674,000	9,204,288,000
Expected remaining maturities of debt securities available-for-sale, amortized cost
Securities available-for-sale, One year or less, amortized cost	664,211,000
Securities available-for-sale, Over 1 year through 5 years, amortized cost	5,023,953,000
Securities available-for-sale, Over 5 years through 10 years, amortized cost	575,790,000
Securities available-for-sale, Over 10 years, amortized cost	3,400,000
Total of debt securities available-for-sale, amortized cost	6,267,354,000
Expected remaining maturities of debt securities held-to-maturity, amortized cost
Securities held-to-maturity, One year or less, amortized cost	44,000
Securities held-to-maturity, Over 1 year through 5 years, amortized cost	782,365,000
Securities held-to-maturity, Over 5 years through 10 years, amortized cost	1,797,139,000
Securities held-to-maturity, Over 10 years, amortized cost	378,295,000
Total of debt securities held-to-maturity, amortized cost	2,957,843,000
U.S. Treasury
Expected remaining maturities of debt securities available-for-sale, fair value
Securities available-for-sale, One year or less, fair value	12,041,000
Securities available-for-sale, Over 1 year through 5 years, fair value	23,294,000
Fair Value	35,335,000	20,397,000
Federal agency - Debt
Expected remaining maturities of debt securities available-for-sale, fair value
Securities available-for-sale, One year or less, fair value	479,705,000
Securities available-for-sale, Over 1 year through 5 years, fair value	872,099,000
Securities available-for-sale, Over 5 years through 10 years, fair value	58,732,000
Fair Value	1,410,536,000	2,349,202,000
Expected remaining maturities of debt securities held-to-maturity, amortized cost
Securities held-to-maturity, Over 5 years through 10 years, amortized cost	58,639,000
Securities held-to-maturity, Over 10 years, amortized cost	119,774,000
Total of debt securities held-to-maturity, amortized cost	178,413,000	97,183,000
Federal agency - MBS
Expected remaining maturities of debt securities available-for-sale, fair value
Securities available-for-sale, One year or less, fair value	54,000
Securities available-for-sale, Over 1 year through 5 years, fair value	95,718,000
Securities available-for-sale, Over 5 years through 10 years, fair value	61,454,000
Fair Value	157,226,000	693,032,000
Expected remaining maturities of debt securities held-to-maturity, amortized cost
Securities held-to-maturity, One year or less, amortized cost	44,000
Securities held-to-maturity, Over 1 year through 5 years, amortized cost	30,001,000
Securities held-to-maturity, Over 5 years through 10 years, amortized cost	403,869,000
Securities held-to-maturity, Over 10 years, amortized cost	11,446,000
Total of debt securities held-to-maturity, amortized cost	445,360,000	303,642,000
CMOs - Federal agency
Expected remaining maturities of debt securities available-for-sale, fair value
Securities available-for-sale, One year or less, fair value	111,773,000
Securities available-for-sale, Over 1 year through 5 years, fair value	3,452,663,000
Securities available-for-sale, Over 5 years through 10 years, fair value	432,862,000
Fair Value	3,997,298,000	5,318,253,000
Expected remaining maturities of debt securities held-to-maturity, amortized cost
Securities held-to-maturity, Over 1 year through 5 years, amortized cost	640,808,000
Securities held-to-maturity, Over 5 years through 10 years, amortized cost	1,140,411,000
Total of debt securities held-to-maturity, amortized cost	1,781,219,000	745,980,000
CMOs - Non-agency
Expected remaining maturities of debt securities available-for-sale, fair value
Securities available-for-sale, Over 1 year through 5 years, fair value	32,182,000
Securities available-for-sale, Over 5 years through 10 years, fair value	5,280,000
Fair Value	37,462,000	61,513,000
State and municipal
Expected remaining maturities of debt securities available-for-sale, fair value
Securities available-for-sale, One year or less, fair value	63,046,000
Securities available-for-sale, Over 1 year through 5 years, fair value	349,613,000
Securities available-for-sale, Over 10 years, fair value	3,336,000
Fair Value	415,995,000	454,474,000
Expected remaining maturities of debt securities held-to-maturity, amortized cost
Securities held-to-maturity, Over 1 year through 5 years, amortized cost	12,860,000
Securities held-to-maturity, Over 5 years through 10 years, amortized cost	194,220,000
Securities held-to-maturity, Over 10 years, amortized cost	247,075,000
Total of debt securities held-to-maturity, amortized cost	454,155,000	251,598,000
Other debt securities
Expected remaining maturities of debt securities available-for-sale, fair value
Securities available-for-sale, Over 1 year through 5 years, fair value	178,822,000
Fair Value	178,822,000	307,417,000
Expected remaining maturities of debt securities held-to-maturity, amortized cost
Securities held-to-maturity, Over 1 year through 5 years, amortized cost	98,696,000
Total of debt securities held-to-maturity, amortized cost	$ 98,696,000