Securities (Details 4) (USD $)																			3 Months Ended
	Jun. 30, 2013	Dec. 31, 2012	Jun. 30, 2013 U.S. Treasury Security	Dec. 31, 2012 U.S. Treasury Security	Jun. 30, 2013 Federal agency - Debt Security	Dec. 31, 2012 Federal agency - Debt Security	Jun. 30, 2013 Federal agency - MBS Security	Dec. 31, 2012 Federal agency - MBS Security	Jun. 30, 2013 CMOs - Federal agency Security	Dec. 31, 2012 CMOs - Federal agency Security	Jun. 30, 2013 CMOs - Non-agency Security	Dec. 31, 2012 CMOs - Non-agency Security	Jun. 30, 2013 State and municipal Security	Dec. 31, 2012 State and municipal Security	Jun. 30, 2013 Other debt securities item Security	Dec. 31, 2012 Other debt securities Security	Jun. 30, 2013 Total debt securities Security	Dec. 31, 2012 Total debt securities Security	Mar. 31, 2013 Collateralized debt obligations item	Jun. 30, 2013 Collateralized debt obligations
Securities available-for-sale:
Securities available-for-sale, Fair Value, Less than 12 months	$ 3,906,678,000	$ 1,940,958,000	$ 15,076,000	$ 5,096,000	$ 776,490,000	$ 346,136,000	$ 100,077,000	$ 50,932,000	$ 2,671,312,000	$ 1,413,367,000	$ 20,744,000		$ 180,366,000	$ 85,550,000	$ 142,613,000	$ 39,877,000
Securities available-for-sale, Estimated Unrealized Loss, Less than 12 months	72,635,000	6,543,000	16,000	3,000	8,933,000	203,000	4,212,000	69,000	55,713,000	5,994,000	870,000		1,991,000	225,000	900,000	49,000
Securities available-for-sale, Fair Value, 12 months or greater	27,702,000	55,943,000					45,000	46,000		13,565,000	8,445,000	25,484,000	3,543,000	810,000	15,669,000	16,038,000
Securities available-for-sale, Estimated Unrealized Loss, 12 months or greater	5,772,000	8,001,000								44,000	1,024,000	2,124,000	57,000	14,000	4,691,000	5,819,000
Securities available-for-sale, Fair Value, Total	3,934,380,000	1,996,901,000	15,076,000	5,096,000	776,490,000	346,136,000	100,122,000	50,978,000	2,671,312,000	1,426,932,000	29,189,000	25,484,000	183,909,000	86,360,000	158,282,000	55,915,000				4,700,000
Securities available-for-sale, Estimated Unrealized Loss, Total	78,407,000	14,544,000	16,000	3,000	8,933,000	203,000	4,212,000	69,000	55,713,000	6,038,000	1,894,000	2,124,000	2,048,000	239,000	5,591,000	5,868,000
Securities held-to-maturity:
Securities held-to-maturity, Fair Value, Less than 12 months	1,090,808,000	156,856,000			80,966,000		233,183,000	31,514,000	549,647,000	60,998,000			227,012,000	64,344,000
Securities held-to-maturity, Estimated Unrealized Loss, Less than 12 months	41,943,000	1,421,000			1,556,000		8,555,000	182,000	16,997,000	382,000			14,835,000	857,000
Securities held-to-maturity, Fair Value, Total	1,090,808,000	156,856,000			80,966,000		233,183,000	31,514,000	549,647,000	60,998,000			227,012,000	64,344,000
Securities held-to-maturity, Estimated Unrealized Loss, Total	41,943,000	1,421,000			1,556,000		8,555,000	182,000	16,997,000	382,000			14,835,000	857,000
Number of highly rated corporate debt and collateralized bond obligations															1
Number of CDO's on which substantial paydown was received																			1
Other information
Fair value securities, having non-credit impairment recognized in AOCI	6,200,000	16,200,000
Number of available-for-sale and held-to-maturity securities in the unrealized loss position			3	2	33	8	29	7	140	53	6	4	462	152	14	5	687	231
Temporarily impaired securities	$ 3,930,000,000	$ 1,980,000,000