Investment Securities (Gross Unrealized Loss Table) (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013 securities	Dec. 31, 2012 securities	Sep. 30, 2012 securities
Securities available for sale
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	$ 1,694,722	$ 213,685	$ 124,987
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	(59,730)	(1,031)	(400)
Available for Sale Securities in Unrealized Loss Positions Less than Twelve Months Qualitative Disclosure Number of Positions	230	41	16
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	50,850	50,056	49,074
available for sale securities, continuous unrealized loss position, 12 months or longer, aggregate loss at end of period	(10,732)	(11,891)	(14,038)
Available for Sale Securities in Unrealized Loss Positions Twelve Months or Longer Qualitative Disclosure Number of Positions	8	11	9
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	1,745,572	263,741	174,061
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss at End of Period	(70,462)	(12,922)	(14,438)
Securities held to maturity
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	2,221,306	23,956	2,360
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	(98,138)	(86)	(17)
Held to Maturity Securities in Unrealized Loss Positions Less than Twelve Months Qualitative Disclosure Number of Positions	489	13	4
Held-to-maturity Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	987	0	0
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	(14)	0	0
Held to Maturity Securities in Unrealized Loss Positions Twelve Months or Longer Qualitative Disclosure Number of Positions	1	0	0
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value	2,222,293	23,956	2,360
Held-to-maturity Securities, Continuous Unrealized Loss Position, Aggregate Losses	(98,152)	(86)	(17)
US Government Agencies Debt Securities
Securities held to maturity
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	23,864
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	(1,136)
Held to Maturity Securities in Unrealized Loss Positions Less than Twelve Months Qualitative Disclosure Number of Positions	1
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 Losses	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	23,864
Held-to-maturity Securities, Continuous Unrealized Loss Position, Aggregate Losses	(1,136)
U.S. States and political subdivisions debt securities
Securities available for sale
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	57,258	14,110	3,560
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	(3,495)	(229)	(21)
Available for Sale Securities in Unrealized Loss Positions Less than Twelve Months Qualitative Disclosure Number of Positions	100	24	8
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	0	0	0
available for sale securities, continuous unrealized loss position, 12 months or longer, aggregate loss at end of period	0	0	0
Available for Sale Securities in Unrealized Loss Positions Twelve Months or Longer Qualitative Disclosure Number of Positions	0	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	57,258	14,110	3,560
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss at End of Period	(3,495)	(229)	(21)
Securities held to maturity
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	226,853	6,543	2,360
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	(9,243)	(70)	(17)
Held to Maturity Securities in Unrealized Loss Positions Less than Twelve Months Qualitative Disclosure Number of Positions	362	12	4
Held-to-maturity Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	987	0	0
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	(14)	0	0
Held to Maturity Securities in Unrealized Loss Positions Twelve Months or Longer Qualitative Disclosure Number of Positions	1	0	0
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value	227,840	6,543	2,360
Held-to-maturity Securities, Continuous Unrealized Loss Position, Aggregate Losses	(9,257)	(70)	(17)
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	309,239	14	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	(10,035)	0	0
Available for Sale Securities in Unrealized Loss Positions Less than Twelve Months Qualitative Disclosure Number of Positions	23	1	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	0	13	0
available for sale securities, continuous unrealized loss position, 12 months or longer, aggregate loss at end of period	0	0	0
Available for Sale Securities in Unrealized Loss Positions Twelve Months or Longer Qualitative Disclosure Number of Positions	0	1	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	309,239	27	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss at End of Period	(10,035)	0	0
Securities held to maturity
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	252,007
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	(8,578)
Held to Maturity Securities in Unrealized Loss Positions Less than Twelve Months Qualitative Disclosure Number of Positions	13
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 Losses	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	252,007
Held-to-maturity Securities, Continuous Unrealized Loss Position, Aggregate Losses	(8,578)
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	50,823	31,237
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	(2,220)	(406)
Available for Sale Securities in Unrealized Loss Positions Less than Twelve Months Qualitative Disclosure Number of Positions	7	3
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	0	0
available for sale securities, continuous unrealized loss position, 12 months or longer, aggregate loss at end of period	0	0
Available for Sale Securities in Unrealized Loss Positions Twelve Months or Longer Qualitative Disclosure Number of Positions	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	50,823	31,237
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss at End of Period	(2,220)	(406)
Securities held to maturity
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	44,168		0
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	(1,025)		0
Held to Maturity Securities in Unrealized Loss Positions Less than Twelve Months Qualitative Disclosure Number of Positions	7		0
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 Losses	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	44,168		0
Held-to-maturity Securities, Continuous Unrealized Loss Position, Aggregate Losses	(1,025)		0
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	1,073,105	133,008	121,427
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	(38,995)	(258)	(379)
Available for Sale Securities in Unrealized Loss Positions Less than Twelve Months Qualitative Disclosure Number of Positions	69	9	8
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	0	389	1,581
available for sale securities, continuous unrealized loss position, 12 months or longer, aggregate loss at end of period	0	(2)	(4)
Available for Sale Securities in Unrealized Loss Positions Twelve Months or Longer Qualitative Disclosure Number of Positions	0	1	1
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	1,073,105	133,397	123,008
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss at End of Period	(38,995)	(260)	(383)
Securities held to maturity
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	1,416,238	17,413
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	(68,719)	(16)
Held to Maturity Securities in Unrealized Loss Positions Less than Twelve Months Qualitative Disclosure Number of Positions	64	1
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 Losses	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	1,416,238	17,413
Held-to-maturity Securities, Continuous Unrealized Loss Position, Aggregate Losses	(68,719)	(16)
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	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses		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		2	0
available for sale securities, continuous unrealized loss position, 12 months or longer, aggregate loss at end of period		0	0
Available for Sale Securities in Unrealized Loss Positions Twelve Months or Longer Qualitative Disclosure Number of Positions		1	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		2	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss at End of Period		0	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	38,938	35,316
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	(1,690)	(138)
Available for Sale Securities in Unrealized Loss Positions Less than Twelve Months Qualitative Disclosure Number of Positions	5	4
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	0	0
available for sale securities, continuous unrealized loss position, 12 months or longer, aggregate loss at end of period	0	0
Available for Sale Securities in Unrealized Loss Positions Twelve Months or Longer Qualitative Disclosure Number of Positions	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	38,938	35,316
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss at End of Period	(1,690)	(138)
Securities held to maturity
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	191,402		0
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	(8,936)		0
Held to Maturity Securities in Unrealized Loss Positions Less than Twelve Months Qualitative Disclosure Number of Positions	18		0
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 Losses	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	191,402		0
Held-to-maturity Securities, Continuous Unrealized Loss Position, Aggregate Losses	(8,936)		0
Collateralized Loan Obligations
Securities available for sale
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	165,359
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	(3,295)
Available for Sale Securities in Unrealized Loss Positions Less than Twelve Months Qualitative Disclosure Number of Positions	26
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	165,359
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss at End of Period	(3,295)
Corporate debt securities
Securities available for sale
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	0	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	0	0	0
Available for Sale Securities in Unrealized Loss Positions Less than Twelve Months Qualitative Disclosure Number of Positions	0	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	50,850	49,652	47,493
available for sale securities, continuous unrealized loss position, 12 months or longer, aggregate loss at end of period	(10,732)	(11,889)	(14,034)
Available for Sale Securities in Unrealized Loss Positions Twelve Months or Longer Qualitative Disclosure Number of Positions	8	8	8
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	50,850	49,652	47,493
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss at End of Period	(10,732)	(11,889)	(14,034)
Securities held to maturity
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	66,774
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	(501)
Held to Maturity Securities in Unrealized Loss Positions Less than Twelve Months Qualitative Disclosure Number of Positions	24
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 Losses	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	66,774
Held-to-maturity Securities, Continuous Unrealized Loss Position, Aggregate Losses	$ (501)