Investment Securities (Gross Unrealized Loss Table) (Details) $ in Thousands	Jun. 30, 2016 USD ($) securities	Dec. 31, 2015 USD ($) securities	Jun. 30, 2015 USD ($) securities
Securities available for sale
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	$ 169,846	$ 1,849,320	$ 1,057,236
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ (2,201)	$ (19,569)	$ (10,569)
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Less than One Year | securities	30	180	139
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	$ 576,936	$ 913,649	$ 1,029,278
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ (18,327)	$ (37,458)	$ (32,871)
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Greater than or Equal to One Year | securities	60	91	97
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	$ 746,782	$ 2,762,969	$ 2,086,514
Available-for-sale Securities, Continuous Unrealized Loss Position, Total	(20,528)	(57,027)	(43,440)
Securities held to maturity
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	22,005	370,605	305,627
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ (61)	$ (2,916)	$ (3,233)
Held to Maturity Securities in Unrealized Loss Positions Less than Twelve Months Qualitative Disclosure Number of Positions | securities	9	58	127
Held-to-maturity Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	$ 652,638	$ 1,171,297	$ 1,329,114
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ (7,326)	$ (40,433)	$ (41,739)
Held to Maturity Securities in Unrealized Loss Positions Twelve Months or Longer Qualitative Disclosure Number of Positions | securities	50	79	83
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value	$ 674,643	$ 1,541,902	$ 1,634,741
Held-to-maturity Securities, Continuous Unrealized Loss Position, Total	(7,387)	(43,349)	(44,972)
US Government Agencies Debt Securities
Securities available for sale
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value		2,498
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss		$ (2)
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Less than One Year | securities		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, Accumulated Loss		$ 0
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Greater than or Equal to One Year | securities		0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		$ 2,498
Available-for-sale Securities, Continuous Unrealized Loss Position, Total		(2)
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, Accumulated Loss			$ 0
Held to Maturity Securities in Unrealized Loss Positions Less than Twelve Months Qualitative Disclosure Number of Positions | securities			0
Held-to-maturity Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value			$ 24,677
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss			$ (323)
Held to Maturity Securities in Unrealized Loss Positions Twelve Months or Longer Qualitative Disclosure Number of Positions | securities			1
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value			$ 24,677
Held-to-maturity Securities, Continuous Unrealized Loss Position, Total			(323)
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	1,567	10,178	32,237
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ (2)	$ (37)	$ (587)
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Less than One Year | securities	3	20	52
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	$ 0	$ 5,899	$ 5,642
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 0	$ (167)	$ (436)
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Greater than or Equal to One Year | securities	0	9	9
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	$ 1,567	$ 16,077	$ 37,879
Available-for-sale Securities, Continuous Unrealized Loss Position, Total	(2)	(204)	(1,023)
Securities held to maturity
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	3,525	18,465	98,867
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ (19)	$ (224)	$ (1,872)
Held to Maturity Securities in Unrealized Loss Positions Less than Twelve Months Qualitative Disclosure Number of Positions | securities	7	21	112
Held-to-maturity Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	$ 6,569	$ 4,174	$ 4,430
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ (246)	$ (38)	$ (70)
Held to Maturity Securities in Unrealized Loss Positions Twelve Months or Longer Qualitative Disclosure Number of Positions | securities	9	6	6
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value	$ 10,094	$ 22,639	$ 103,297
Held-to-maturity Securities, Continuous Unrealized Loss Position, Total	(265)	(262)	(1,942)
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	14,275	328,156	196,219
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ (67)	$ (3,026)	$ (2,087)
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Less than One Year | securities	5	27	15
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	$ 0	$ 95,895	$ 103,498
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 0	$ (2,428)	$ (2,476)
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Greater than or Equal to One Year | securities	0	7	8
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	$ 14,275	$ 424,051	$ 299,717
Available-for-sale Securities, Continuous Unrealized Loss Position, Total	(67)	(5,454)	(4,563)
Securities held to maturity
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	0	85,738	83,112
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ 0	$ (715)	$ (483)
Held to Maturity Securities in Unrealized Loss Positions Less than Twelve Months Qualitative Disclosure Number of Positions | securities	0	6	5
Held-to-maturity Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	$ 0	$ 97,880	$ 105,289
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 0	$ (2,284)	$ (2,457)
Held to Maturity Securities in Unrealized Loss Positions Twelve Months or Longer Qualitative Disclosure Number of Positions | securities	0	6	6
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value	$ 0	$ 183,618	$ 188,401
Held-to-maturity Securities, Continuous Unrealized Loss Position, Total	0	(2,999)	(2,940)
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	23,570	107,074	96,573
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ (28)	$ (1,447)	$ (1,457)
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Less than One Year | securities	1	15	14
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	$ 12,627	$ 12,401	$ 17,335
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ (88)	$ (576)	$ (690)
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Greater than or Equal to One Year | securities	1	1	2
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	$ 36,197	$ 119,475	$ 113,908
Available-for-sale Securities, Continuous Unrealized Loss Position, Total	(116)	(2,023)	(2,147)
Securities held to maturity
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	13,478	34,833	7,263
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ (42)	$ (346)	$ (41)
Held to Maturity Securities in Unrealized Loss Positions Less than Twelve Months Qualitative Disclosure Number of Positions | securities	1	6	1
Held-to-maturity Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	$ 0	$ 9,269	$ 9,430
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ 0	$ (228)	$ (178)
Held to Maturity Securities in Unrealized Loss Positions Twelve Months or Longer Qualitative Disclosure Number of Positions | securities	0	1	1
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value	$ 13,478	$ 44,102	$ 16,693
Held-to-maturity Securities, Continuous Unrealized Loss Position, Total	(42)	(574)	(219)
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	13,182	1,130,779	596,646
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ (271)	$ (10,587)	$ (4,398)
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Less than One Year | securities	1	78	42
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	$ 332,305	$ 597,403	$ 706,376
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ (2,818)	$ (19,560)	$ (19,910)
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Greater than or Equal to One Year | securities	29	49	53
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	$ 345,487	$ 1,728,182	$ 1,303,022
Available-for-sale Securities, Continuous Unrealized Loss Position, Total	(3,089)	(30,147)	(24,308)
Securities held to maturity
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	0	140,514	111,360
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ 0	$ (1,225)	$ (835)
Held to Maturity Securities in Unrealized Loss Positions Less than Twelve Months Qualitative Disclosure Number of Positions | securities	0	12	8
Held-to-maturity Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	$ 598,383	$ 941,982	$ 1,042,351
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ (6,670)	$ (34,656)	$ (34,190)
Held to Maturity Securities in Unrealized Loss Positions Twelve Months or Longer Qualitative Disclosure Number of Positions | securities	37	55	56
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value	$ 598,383	$ 1,082,496	$ 1,153,711
Held-to-maturity Securities, Continuous Unrealized Loss Position, Total	(6,670)	(35,881)	(35,025)
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	24,401	113,825	46,771
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ (38)	$ (893)	$ (71)
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Less than One Year | securities	4	12	5
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	$ 19,071	$ 23,400	$ 61,120
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ (84)	$ (376)	$ (634)
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Greater than or Equal to One Year | securities	1	2	7
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	$ 43,472	$ 137,225	$ 107,891
Available-for-sale Securities, Continuous Unrealized Loss Position, Total	(122)	(1,269)	(705)
Securities held to maturity
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	0	71,812	5,025
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ 0	$ (384)	$ (2)
Held to Maturity Securities in Unrealized Loss Positions Less than Twelve Months Qualitative Disclosure Number of Positions | securities	0	7	1
Held-to-maturity Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	$ 47,686	$ 117,992	$ 142,937
Held-to-maturity Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ (410)	$ (3,227)	$ (4,521)
Held to Maturity Securities in Unrealized Loss Positions Twelve Months or Longer Qualitative Disclosure Number of Positions | securities	4	11	13
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value	$ 47,686	$ 189,804	$ 147,962
Held-to-maturity Securities, Continuous Unrealized Loss Position, Total	(410)	(3,611)	(4,523)
Collateralized Loan Obligations
Securities available for sale
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	92,851	151,810	84,565
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ (1,795)	$ (3,576)	$ (1,204)
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Less than One Year | securities	16	26	10
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	$ 161,827	$ 126,422	$ 86,082
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ (4,704)	$ (4,870)	$ (1,259)
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Greater than or Equal to One Year | securities	21	15	11
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	$ 254,678	$ 278,232	$ 170,647
Available-for-sale Securities, Continuous Unrealized Loss Position, Total	(6,499)	(8,446)	(2,463)
Corporate debt securities
Securities available for sale
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value		0	4,225
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss		$ 0	$ (765)
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Less than One Year | securities		0	1
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	$ 51,106	$ 52,229	$ 49,225
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	$ (10,633)	$ (9,481)	$ (7,466)
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Greater than or Equal to One Year | securities	8	8	7
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	$ 51,106	$ 52,229	$ 53,450
Available-for-sale Securities, Continuous Unrealized Loss Position, Total	(10,633)	(9,481)	$ (8,231)
Securities held to maturity
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	5,002	19,243
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ 0	$ (22)
Held to Maturity Securities in Unrealized Loss Positions Less than Twelve Months Qualitative Disclosure Number of Positions | securities	1	6
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, Accumulated Loss	$ 0	$ 0
Held to Maturity Securities in Unrealized Loss Positions Twelve Months or Longer Qualitative Disclosure Number of Positions | securities	0	0
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value	$ 5,002	$ 19,243
Held-to-maturity Securities, Continuous Unrealized Loss Position, Total	$ 0	(22)
US Treasury Securities
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, Less than 12 Months, Accumulated Loss		$ (1)
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Less than One Year | securities		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, Accumulated Loss		$ 0
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Greater than or Equal to One Year | securities		0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		$ 5,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Total		$ (1)