Investment Securities (Details 2) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	$ 594,960	$ 1,377,664
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss	(8,067)	(13,632)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	56,074	41,832
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss	(1,901)	(1,473)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	651,034	1,419,496
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss	(9,968)	(15,105)
Government agency and government-sponsored enterprise pass through securities
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	196,388	391,642
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss	(1,135)	(3,893)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	9,422	9,342
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss	(98)	(266)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	205,810	400,984
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss	(1,233)	(4,159)
Government agency and government-sponsored enterprise collateralized mortgage obligations
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	33,702	314,284
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss	(239)	(2,769)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	0	14,230
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss	0	(641)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	33,702	328,514
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss	(239)	(3,410)
Covered private label collateralized mortgage obligation
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	1,239	1,354
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss	(98)	(57)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	849	568
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss	(129)	(68)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	2,088	1,922
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss	(227)	(125)
Other Private Label Collateralized Mortgage Obligations
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	59,407	92,179
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss	(838)	(943)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	1,029	1,070
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss	(45)	(38)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	60,436	93,249
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss	(883)	(981)
Municipal securities
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	18,108	126,892
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss	(55)	(1,061)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	5,496	531
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss	(34)	(11)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	23,604	127,423
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss	(89)	(1,072)
US Treasury Securities
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value		69,380
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss		(816)
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		0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		69,380
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss		(816)
Corporate Debt Securities
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	28,180	29,379
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss	(2,089)	(950)
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	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	28,180	29,379
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss	(2,089)	(950)
Collateralized Loan Obligations
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	106,773	100,993
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss	(2,121)	(1,131)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	23,355	0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss	(986)	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	130,128	100,993
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss	(3,107)	(1,131)
Asset-backed Securities
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	87,150	179,942
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss	(207)	(830)
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	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	87,150	179,942
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss	(207)	(830)
Asset-backed and other securities
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	64,013	71,619
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Loss	(1,285)	(1,182)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	15,923	16,091
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss	(609)	(449)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	79,936	87,710
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss	$ (1,894)	$ (1,631)