Investment Securities (Gross Unrealized Loss Table) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Securities available for sale
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	$ 424,916	$ 1,908,543
Available-for-sale Securities, Continous Unrealized Loss Position, Less than 12 Months, Aggregate Loss as of Period End	(2,807)	(67,758)
Available for Sale Securities in Unrealized Loss Positions Less than Twelve Months Qualitative Disclosure Number of Positions	53	218
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	1,485,458	199,691
available for sale securities, continuous unrealized loss position, 12 months or longer, aggregate loss at end of period	(49,824)	(22,462)
Available for Sale Securities in Unrealized Loss Positions Twelve Months or Longer Qualitative Disclosure Number of Positions	162	46
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	1,910,374	2,108,234
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss at End of Period	(52,631)	(90,220)
Securities held to maturity
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	125,775	2,373,148
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss as of Period End	(277)	(118,026)
Held to Maturity Securities in Unrealized Loss Positions Less than Twelve Months Qualitative Disclosure Number of Positions	30	492
Held-to-maturity Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	1,577,797	2,478
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss at End of Period	(49,520)	(183)
Held to Maturity Securities in Unrealized Loss Positions Twelve Months or Longer Qualitative Disclosure Number of Positions	108	6
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value	1,703,572	2,375,626
Held-to-Maturity Securities, Continuous Unrealized Loss Position, Aggregate Loss at End of Period	(49,797)	(118,209)
U.S. Government agencies
Securities available for sale
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	2,482
Available-for-sale Securities, Continous Unrealized Loss Position, Less than 12 Months, Aggregate Loss as of Period End	(18)
Available for Sale Securities in Unrealized Loss Positions Less than Twelve Months Qualitative Disclosure Number of Positions	1
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	0
available for sale securities, continuous unrealized loss position, 12 months or longer, aggregate loss at end of period	0
Available for Sale Securities in Unrealized Loss Positions Twelve Months or Longer Qualitative Disclosure Number of Positions	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	2,482
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss at End of Period	(18)
Securities held to maturity
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	0	23,652
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss as of Period End	0	(1,348)
Held to Maturity Securities in Unrealized Loss Positions Less than Twelve Months Qualitative Disclosure Number of Positions	0	1
Held-to-maturity Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	24,463	0
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss at End of Period	(537)	0
Held to Maturity Securities in Unrealized Loss Positions Twelve Months or Longer Qualitative Disclosure Number of Positions	1	0
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value	24,463	23,652
Held-to-Maturity Securities, Continuous Unrealized Loss Position, Aggregate Loss at End of Period	(537)	(1,348)
U.S. States and political subdivisions
Securities available for sale
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	5,637	38,039
Available-for-sale Securities, Continous Unrealized Loss Position, Less than 12 Months, Aggregate Loss as of Period End	(11)	(1,996)
Available for Sale Securities in Unrealized Loss Positions Less than Twelve Months Qualitative Disclosure Number of Positions	11	65
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	22,528	14,157
available for sale securities, continuous unrealized loss position, 12 months or longer, aggregate loss at end of period	(455)	(1,800)
Available for Sale Securities in Unrealized Loss Positions Twelve Months or Longer Qualitative Disclosure Number of Positions	36	25
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	28,165	52,196
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss at End of Period	(466)	(3,796)
Securities held to maturity
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	9,085	222,154
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss as of Period End	(17)	(10,276)
Held to Maturity Securities in Unrealized Loss Positions Less than Twelve Months Qualitative Disclosure Number of Positions	9	353
Held-to-maturity Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	18,371	2,478
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss at End of Period	(174)	(183)
Held to Maturity Securities in Unrealized Loss Positions Twelve Months or Longer Qualitative Disclosure Number of Positions	21	6
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value	27,456	224,632
Held-to-Maturity Securities, Continuous Unrealized Loss Position, Aggregate Loss at End of Period	(191)	(10,459)
Residential Mortgage Backed Securities Issued by US Government Sponsored Enterprises
Securities available for sale
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	50,126	434,761
Available-for-sale Securities, Continous Unrealized Loss Position, Less than 12 Months, Aggregate Loss as of Period End	(182)	(13,109)
Available for Sale Securities in Unrealized Loss Positions Less than Twelve Months Qualitative Disclosure Number of Positions	5	35
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	199,773	14,890
available for sale securities, continuous unrealized loss position, 12 months or longer, aggregate loss at end of period	(3,036)	(1,318)
Available for Sale Securities in Unrealized Loss Positions Twelve Months or Longer Qualitative Disclosure Number of Positions	14	2
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	249,899	449,651
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss at End of Period	(3,218)	(14,427)
Securities held to maturity
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	0	422,192
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss as of Period End	0	(11,617)
Held to Maturity Securities in Unrealized Loss Positions Less than Twelve Months Qualitative Disclosure Number of Positions	0	22
Held-to-maturity Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	185,361	0
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss at End of Period	(3,045)	0
Held to Maturity Securities in Unrealized Loss Positions Twelve Months or Longer Qualitative Disclosure Number of Positions	10	0
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value	185,361	422,192
Held-to-Maturity Securities, Continuous Unrealized Loss Position, Aggregate Loss at End of Period	(3,045)	(11,617)
Commercial Mortgage Backed Securities Issued by US Government Sponsored Enterprises
Securities available for sale
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	12,284	33,387
Available-for-sale Securities, Continous Unrealized Loss Position, Less than 12 Months, Aggregate Loss as of Period End	(55)	(1,491)
Available for Sale Securities in Unrealized Loss Positions Less than Twelve Months Qualitative Disclosure Number of Positions	2	5
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	45,485	16,944
available for sale securities, continuous unrealized loss position, 12 months or longer, aggregate loss at end of period	(1,316)	(997)
Available for Sale Securities in Unrealized Loss Positions Twelve Months or Longer Qualitative Disclosure Number of Positions	6	2
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	57,769	50,331
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss at End of Period	(1,371)	(2,488)
Securities held to maturity
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	9,950	48,831
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss as of Period End	(4)	(1,190)
Held to Maturity Securities in Unrealized Loss Positions Less than Twelve Months Qualitative Disclosure Number of Positions	2	8
Held-to-maturity Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	16,735	0
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss at End of Period	(325)	0
Held to Maturity Securities in Unrealized Loss Positions Twelve Months or Longer Qualitative Disclosure Number of Positions	2	0
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value	26,685	48,831
Held-to-Maturity Securities, Continuous Unrealized Loss Position, Aggregate Loss at End of Period	(329)	(1,190)
Residential Collateralized Mortgage-Backed Securities Issued by US Government Sponsored Enterprises
Securities available for sale
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	243,970	1,135,151
Available-for-sale Securities, Continous Unrealized Loss Position, Less than 12 Months, Aggregate Loss as of Period End	(906)	(44,775)
Available for Sale Securities in Unrealized Loss Positions Less than Twelve Months Qualitative Disclosure Number of Positions	15	74
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	905,478	100,530
available for sale securities, continuous unrealized loss position, 12 months or longer, aggregate loss at end of period	(25,319)	(7,293)
Available for Sale Securities in Unrealized Loss Positions Twelve Months or Longer Qualitative Disclosure Number of Positions	64	7
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	1,149,448	1,235,681
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss at End of Period	(26,225)	(52,068)
Securities held to maturity
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	28,333	1,382,915
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss as of Period End	(149)	(81,818)
Held to Maturity Securities in Unrealized Loss Positions Less than Twelve Months Qualitative Disclosure Number of Positions	3	66
Held-to-maturity Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	1,161,297	0
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss at End of Period	(38,726)	0
Held to Maturity Securities in Unrealized Loss Positions Twelve Months or Longer Qualitative Disclosure Number of Positions	58	0
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value	1,189,630	1,382,915
Held-to-Maturity Securities, Continuous Unrealized Loss Position, Aggregate Loss at End of Period	(38,875)	(81,818)
Residential Collateralized Mortgage-Backed Securities Issued by Non-US Government Agency
Securities available for sale
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value		0
Available-for-sale Securities, Continous Unrealized Loss Position, Less than 12 Months, Aggregate Loss as of Period End		0
Available for Sale Securities in Unrealized Loss Positions Less than Twelve Months Qualitative Disclosure Number of Positions		0
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		1
available for sale securities, continuous unrealized loss position, 12 months or longer, aggregate loss at end of period		0
Available for Sale Securities in Unrealized Loss Positions Twelve Months or Longer Qualitative Disclosure Number of Positions		1
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		1
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss at End of Period		0
Securities held to maturity
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value		0
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss as of Period End		0
Held to Maturity Securities in Unrealized Loss Positions Less than Twelve Months Qualitative Disclosure Number of Positions		0
Held-to-maturity Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		0
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss at End of Period		0
Held to Maturity Securities in Unrealized Loss Positions Twelve Months or Longer Qualitative Disclosure Number of Positions		0
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value		0
Held-to-Maturity Securities, Continuous Unrealized Loss Position, Aggregate Loss at End of Period		0
Commercial Collateralized Mortgage Backed Securities Issued by US Government Sponsored Enterprises
Securities available for sale
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	31,375	43,747
Available-for-sale Securities, Continous Unrealized Loss Position, Less than 12 Months, Aggregate Loss as of Period End	(229)	(2,055)
Available for Sale Securities in Unrealized Loss Positions Less than Twelve Months Qualitative Disclosure Number of Positions	4	6
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	67,169	2,525
available for sale securities, continuous unrealized loss position, 12 months or longer, aggregate loss at end of period	(1,176)	(102)
Available for Sale Securities in Unrealized Loss Positions Twelve Months or Longer Qualitative Disclosure Number of Positions	7	1
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	98,544	46,272
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss at End of Period	(1,405)	(2,157)
Securities held to maturity
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	41,474	208,863
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss as of Period End	(55)	(11,052)
Held to Maturity Securities in Unrealized Loss Positions Less than Twelve Months Qualitative Disclosure Number of Positions	3	19
Held-to-maturity Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	171,570	0
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss at End of Period	(6,713)	0
Held to Maturity Securities in Unrealized Loss Positions Twelve Months or Longer Qualitative Disclosure Number of Positions	16	0
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value	213,044	208,863
Held-to-Maturity Securities, Continuous Unrealized Loss Position, Aggregate Loss at End of Period	(6,768)	(11,052)
Collateralized Loan Obligations
Securities available for sale
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	79,042	223,458
Available-for-sale Securities, Continous Unrealized Loss Position, Less than 12 Months, Aggregate Loss as of Period End	(1,406)	(4,332)
Available for Sale Securities in Unrealized Loss Positions Less than Twelve Months Qualitative Disclosure Number of Positions	15	33
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	193,687	0
available for sale securities, continuous unrealized loss position, 12 months or longer, aggregate loss at end of period	(8,207)	0
Available for Sale Securities in Unrealized Loss Positions Twelve Months or Longer Qualitative Disclosure Number of Positions	27	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	272,729	223,458
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss at End of Period	(9,613)	(4,332)
Corporate bonds
Securities available for sale
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	0	0
Available-for-sale Securities, Continous Unrealized Loss Position, Less than 12 Months, Aggregate Loss as of Period End	0	0
Available for Sale Securities in Unrealized Loss Positions Less than Twelve Months Qualitative Disclosure Number of Positions	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	51,338	50,644
available for sale securities, continuous unrealized loss position, 12 months or longer, aggregate loss at end of period	(10,315)	(10,952)
Available for Sale Securities in Unrealized Loss Positions Twelve Months or Longer Qualitative Disclosure Number of Positions	8	8
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	51,338	50,644
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss at End of Period	(10,315)	(10,952)
Securities held to maturity
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	36,933	64,541
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss as of Period End	(52)	(725)
Held to Maturity Securities in Unrealized Loss Positions Less than Twelve Months Qualitative Disclosure Number of Positions	13	23
Held-to-maturity Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	0	0
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss at End of Period	0	0
Held to Maturity Securities in Unrealized Loss Positions Twelve Months or Longer Qualitative Disclosure Number of Positions	0	0
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value	36,933	64,541
Held-to-Maturity Securities, Continuous Unrealized Loss Position, Aggregate Loss at End of Period	$ (52)	$ (725)