Investment Securities (Gross Unrealized Loss) (Details) $ in Thousands	Dec. 31, 2015 USD ($) securities	Dec. 31, 2014 USD ($) securities
Securities available for sale
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	$ 1,849,320	$ 424,916
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	913,649	1,485,458
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	2,762,969	1,910,374
Available-for-sale Securities, Continous Unrealized Loss Position, Less than 12 Months, Aggregate Loss as of Period End	(19,569)	(2,807)
Available for sale securities, continuous unrealized loss position, 12 months or longer, aggregate loss at end of period	(37,458)	(49,824)
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss at End of Period	$ (57,027)	$ (52,631)
Available for Sale Securities in Unrealized Loss Positions Less than Twelve Months Qualitative Disclosure Number of Positions | securities	180	53
Available for Sale Securities in Unrealized Loss Positions Twelve Months or Longer Qualitative Disclosure Number of Positions | securities	91	162
Securities held to maturity
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	$ 370,605	$ 125,775
Held-to-maturity Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	1,171,297	1,577,797
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value	1,541,902	1,703,572
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss as of Period End	(2,916)	(277)
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss at End of Period	(40,433)	(49,520)
Held-to-Maturity Securities, Continuous Unrealized Loss Position, Aggregate Loss at End of Period	$ (43,349)	$ (49,797)
Held to Maturity Securities in Unrealized Loss Positions Less than Twelve Months Qualitative Disclosure Number of Positions | securities	58	30
Held to Maturity Securities in Unrealized Loss Positions Twelve Months or Longer Qualitative Disclosure Number of Positions | securities	79	108
U.S. Government agencies
Securities available for sale
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	$ 2,498	$ 2,482
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	2,498	2,482
Available-for-sale Securities, Continous Unrealized Loss Position, Less than 12 Months, Aggregate Loss as of Period End	(2)	(18)
Available for sale securities, continuous unrealized loss position, 12 months or longer, aggregate loss at end of period	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss at End of Period	$ (2)	$ (18)
Available for Sale Securities in Unrealized Loss Positions Less than Twelve Months Qualitative Disclosure Number of Positions | securities	1	1
Available for Sale Securities in Unrealized Loss Positions Twelve Months or Longer Qualitative Disclosure Number of Positions | securities	0	0
Securities held to maturity
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	$ 0	$ 0
Held-to-maturity Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	0	24,463
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value	0	24,463
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss as of Period End	0	0
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss at End of Period	0	(537)
Held-to-Maturity Securities, Continuous Unrealized Loss Position, Aggregate Loss at End of Period	$ 0	$ (537)
Held to Maturity Securities in Unrealized Loss Positions Less than Twelve Months Qualitative Disclosure Number of Positions | securities	0	0
Held to Maturity Securities in Unrealized Loss Positions Twelve Months or Longer Qualitative Disclosure Number of Positions | securities	0	1
U.S. Treasury obligations
Securities available for sale
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	$ 5,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	5,000
Available-for-sale Securities, Continous Unrealized Loss Position, Less than 12 Months, Aggregate Loss as of Period End	(1)
Available for sale securities, continuous unrealized loss position, 12 months or longer, aggregate loss at end of period	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss at End of Period	$ (1)
Available for Sale Securities in Unrealized Loss Positions Less than Twelve Months Qualitative Disclosure Number of Positions | securities	1
Available for Sale Securities in Unrealized Loss Positions Twelve Months or Longer Qualitative Disclosure Number of Positions | securities	0
U.S. States and political subdivisions
Securities available for sale
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	$ 10,178	$ 5,637
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	5,899	22,528
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	16,077	28,165
Available-for-sale Securities, Continous Unrealized Loss Position, Less than 12 Months, Aggregate Loss as of Period End	(37)	(11)
Available for sale securities, continuous unrealized loss position, 12 months or longer, aggregate loss at end of period	(167)	(455)
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss at End of Period	$ (204)	$ (466)
Available for Sale Securities in Unrealized Loss Positions Less than Twelve Months Qualitative Disclosure Number of Positions | securities	20	11
Available for Sale Securities in Unrealized Loss Positions Twelve Months or Longer Qualitative Disclosure Number of Positions | securities	9	36
Securities held to maturity
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	$ 18,465	$ 9,085
Held-to-maturity Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	4,174	18,371
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value	22,639	27,456
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss as of Period End	(224)	(17)
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss at End of Period	(38)	(174)
Held-to-Maturity Securities, Continuous Unrealized Loss Position, Aggregate Loss at End of Period	$ (262)	$ (191)
Held to Maturity Securities in Unrealized Loss Positions Less than Twelve Months Qualitative Disclosure Number of Positions | securities	21	9
Held to Maturity Securities in Unrealized Loss Positions Twelve Months or Longer Qualitative Disclosure Number of Positions | securities	6	21
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	$ 328,156	$ 50,126
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	95,895	199,773
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	424,051	249,899
Available-for-sale Securities, Continous Unrealized Loss Position, Less than 12 Months, Aggregate Loss as of Period End	(3,026)	(182)
Available for sale securities, continuous unrealized loss position, 12 months or longer, aggregate loss at end of period	(2,428)	(3,036)
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss at End of Period	$ (5,454)	$ (3,218)
Available for Sale Securities in Unrealized Loss Positions Less than Twelve Months Qualitative Disclosure Number of Positions | securities	27	5
Available for Sale Securities in Unrealized Loss Positions Twelve Months or Longer Qualitative Disclosure Number of Positions | securities	7	14
Securities held to maturity
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	$ 85,738	$ 0
Held-to-maturity Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	97,880	185,361
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value	183,618	185,361
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss as of Period End	(715)	0
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss at End of Period	(2,284)	(3,045)
Held-to-Maturity Securities, Continuous Unrealized Loss Position, Aggregate Loss at End of Period	$ (2,999)	$ (3,045)
Held to Maturity Securities in Unrealized Loss Positions Less than Twelve Months Qualitative Disclosure Number of Positions | securities	6	0
Held to Maturity Securities in Unrealized Loss Positions Twelve Months or Longer Qualitative Disclosure Number of Positions | securities	6	10
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	$ 107,074	$ 12,284
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	12,401	45,485
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	119,475	57,769
Available-for-sale Securities, Continous Unrealized Loss Position, Less than 12 Months, Aggregate Loss as of Period End	(1,447)	(55)
Available for sale securities, continuous unrealized loss position, 12 months or longer, aggregate loss at end of period	(576)	(1,316)
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss at End of Period	$ (2,023)	$ (1,371)
Available for Sale Securities in Unrealized Loss Positions Less than Twelve Months Qualitative Disclosure Number of Positions | securities	15	2
Available for Sale Securities in Unrealized Loss Positions Twelve Months or Longer Qualitative Disclosure Number of Positions | securities	1	6
Securities held to maturity
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	$ 34,833	$ 9,950
Held-to-maturity Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	9,269	16,735
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value	44,102	26,685
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss as of Period End	(346)	(4)
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss at End of Period	(228)	(325)
Held-to-Maturity Securities, Continuous Unrealized Loss Position, Aggregate Loss at End of Period	$ (574)	$ (329)
Held to Maturity Securities in Unrealized Loss Positions Less than Twelve Months Qualitative Disclosure Number of Positions | securities	6	2
Held to Maturity Securities in Unrealized Loss Positions Twelve Months or Longer Qualitative Disclosure Number of Positions | securities	1	2
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	$ 1,130,779	$ 243,970
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	597,403	905,478
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	1,728,182	1,149,448
Available-for-sale Securities, Continous Unrealized Loss Position, Less than 12 Months, Aggregate Loss as of Period End	(10,587)	(906)
Available for sale securities, continuous unrealized loss position, 12 months or longer, aggregate loss at end of period	(19,560)	(25,319)
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss at End of Period	$ (30,147)	$ (26,225)
Available for Sale Securities in Unrealized Loss Positions Less than Twelve Months Qualitative Disclosure Number of Positions | securities	78	15
Available for Sale Securities in Unrealized Loss Positions Twelve Months or Longer Qualitative Disclosure Number of Positions | securities	49	64
Securities held to maturity
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	$ 140,514	$ 28,333
Held-to-maturity Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	941,982	1,161,297
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value	1,082,496	1,189,630
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss as of Period End	(1,225)	(149)
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss at End of Period	(34,656)	(38,726)
Held-to-Maturity Securities, Continuous Unrealized Loss Position, Aggregate Loss at End of Period	$ (35,881)	$ (38,875)
Held to Maturity Securities in Unrealized Loss Positions Less than Twelve Months Qualitative Disclosure Number of Positions | securities	12	3
Held to Maturity Securities in Unrealized Loss Positions Twelve Months or Longer Qualitative Disclosure Number of Positions | securities	55	58
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	$ 113,825	$ 31,375
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	23,400	67,169
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	137,225	98,544
Available-for-sale Securities, Continous Unrealized Loss Position, Less than 12 Months, Aggregate Loss as of Period End	(893)	(229)
Available for sale securities, continuous unrealized loss position, 12 months or longer, aggregate loss at end of period	(376)	(1,176)
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss at End of Period	$ (1,269)	$ (1,405)
Available for Sale Securities in Unrealized Loss Positions Less than Twelve Months Qualitative Disclosure Number of Positions | securities	12	4
Available for Sale Securities in Unrealized Loss Positions Twelve Months or Longer Qualitative Disclosure Number of Positions | securities	2	7
Securities held to maturity
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	$ 71,812	$ 41,474
Held-to-maturity Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	117,992	171,570
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value	189,804	213,044
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss as of Period End	(384)	(55)
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss at End of Period	(3,227)	(6,713)
Held-to-Maturity Securities, Continuous Unrealized Loss Position, Aggregate Loss at End of Period	$ (3,611)	$ (6,768)
Held to Maturity Securities in Unrealized Loss Positions Less than Twelve Months Qualitative Disclosure Number of Positions | securities	7	3
Held to Maturity Securities in Unrealized Loss Positions Twelve Months or Longer Qualitative Disclosure Number of Positions | securities	11	16
Collateralized Loan Obligations
Securities available for sale
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	$ 151,810	$ 79,042
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	126,422	193,687
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	278,232	272,729
Available-for-sale Securities, Continous Unrealized Loss Position, Less than 12 Months, Aggregate Loss as of Period End	(3,576)	(1,406)
Available for sale securities, continuous unrealized loss position, 12 months or longer, aggregate loss at end of period	(4,870)	(8,207)
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss at End of Period	$ (8,446)	$ (9,613)
Available for Sale Securities in Unrealized Loss Positions Less than Twelve Months Qualitative Disclosure Number of Positions | securities	26	15
Available for Sale Securities in Unrealized Loss Positions Twelve Months or Longer Qualitative Disclosure Number of Positions | securities	15	27
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, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	52,229	51,338
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	52,229	51,338
Available-for-sale Securities, Continous Unrealized Loss Position, Less than 12 Months, Aggregate Loss as of Period End	0	0
Available for sale securities, continuous unrealized loss position, 12 months or longer, aggregate loss at end of period	(9,481)	(10,315)
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss at End of Period	$ (9,481)	$ (10,315)
Available for Sale Securities in Unrealized Loss Positions Less than Twelve Months Qualitative Disclosure Number of Positions | securities	0	0
Available for Sale Securities in Unrealized Loss Positions Twelve Months or Longer Qualitative Disclosure Number of Positions | securities	8	8
Securities held to maturity
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	$ 19,243	$ 36,933
Held-to-maturity Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	0	0
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value	19,243	36,933
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss as of Period End	(22)	(52)
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss at End of Period	0	0
Held-to-Maturity Securities, Continuous Unrealized Loss Position, Aggregate Loss at End of Period	$ (22)	$ (52)
Held to Maturity Securities in Unrealized Loss Positions Less than Twelve Months Qualitative Disclosure Number of Positions | securities	6	13
Held to Maturity Securities in Unrealized Loss Positions Twelve Months or Longer Qualitative Disclosure Number of Positions | securities	0	0