Investment Securities (Details 1) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Unrealized Losses on Securities Available-for-Sale, Less than 12 Months, Fair Value	$ 1,971,330	$ 1,026,780
Unrealized Losses on Securities Available-for-Sale, Less than 12 Months, Gross Unrealized Losses	(38,163)	(8,928)
Unrealized Losses on Securities Available-for-Sale, 12 Months or Longer, Fair Value	153,331	223,832
Unrealized Losses on Securities Available-for-Sale, 12 Months or Longer, Gross Unrealized Losses	(7,171)	(7,131)
Unrealized Losses on Securities Available-for-Sale, Fair Value	2,124,661	1,250,612
Unrealized Losses on Securities Available-for-Sale, Gross Unrealized Losses	(45,334)	(16,059)
Government agency and government-sponsored enterprise pass through securities
Unrealized Losses on Securities Available-for-Sale, Less than 12 Months, Fair Value	104,277	44,795
Unrealized Losses on Securities Available-for-Sale, Less than 12 Months, Gross Unrealized Losses	(1,649)	(311)
Unrealized Losses on Securities Available-for-Sale, 12 Months or Longer, Fair Value	24,518	26,010
Unrealized Losses on Securities Available-for-Sale, 12 Months or Longer, Gross Unrealized Losses	(908)	(533)
Unrealized Losses on Securities Available-for-Sale, Fair Value	128,795	70,805
Unrealized Losses on Securities Available-for-Sale, Gross Unrealized Losses	(2,557)	(844)
Government agency and government-sponsored enterprise collateralized mortgage obligations
Unrealized Losses on Securities Available-for-Sale, Less than 12 Months, Fair Value	251,805	163,014
Unrealized Losses on Securities Available-for-Sale, Less than 12 Months, Gross Unrealized Losses	(5,359)	(2,452)
Unrealized Losses on Securities Available-for-Sale, 12 Months or Longer, Fair Value	18,377	20,928
Unrealized Losses on Securities Available-for-Sale, 12 Months or Longer, Gross Unrealized Losses	(557)	(445)
Unrealized Losses on Securities Available-for-Sale, Fair Value	270,182	183,942
Unrealized Losses on Securities Available-for-Sale, Gross Unrealized Losses	(5,916)	(2,897)
Private label collateralized mortgage obligations
Unrealized Losses on Securities Available-for-Sale, Less than 12 Months, Fair Value	92,396	50,521
Unrealized Losses on Securities Available-for-Sale, Less than 12 Months, Gross Unrealized Losses	(1,105)	(500)
Unrealized Losses on Securities Available-for-Sale, 12 Months or Longer, Fair Value	4,446	5,035
Unrealized Losses on Securities Available-for-Sale, 12 Months or Longer, Gross Unrealized Losses	(107)	(142)
Unrealized Losses on Securities Available-for-Sale, Fair Value	96,842	55,556
Unrealized Losses on Securities Available-for-Sale, Gross Unrealized Losses	(1,212)	(642)
Municipal securities
Unrealized Losses on Securities Available-for-Sale, Less than 12 Months, Fair Value	364,270	67,936
Unrealized Losses on Securities Available-for-Sale, Less than 12 Months, Gross Unrealized Losses	(6,320)	(365)
Unrealized Losses on Securities Available-for-Sale, 12 Months or Longer, Fair Value	30,973	32,326
Unrealized Losses on Securities Available-for-Sale, 12 Months or Longer, Gross Unrealized Losses	(1,744)	(974)
Unrealized Losses on Securities Available-for-Sale, Fair Value	395,243	100,262
Unrealized Losses on Securities Available-for-Sale, Gross Unrealized Losses	(8,064)	(1,339)
Government agency and government-sponsored enterprise commercial mortgage-backed securities
Unrealized Losses on Securities Available-for-Sale, Less than 12 Months, Fair Value	1,006,897	579,373
Unrealized Losses on Securities Available-for-Sale, Less than 12 Months, Gross Unrealized Losses	(21,302)	(3,777)
Unrealized Losses on Securities Available-for-Sale, 12 Months or Longer, Fair Value	67,387	129,060
Unrealized Losses on Securities Available-for-Sale, 12 Months or Longer, Gross Unrealized Losses	(3,755)	(4,981)
Unrealized Losses on Securities Available-for-Sale, Fair Value	1,074,284	708,433
Unrealized Losses on Securities Available-for-Sale, Gross Unrealized Losses	(25,057)	(8,758)
SBA asset-backed securities
Unrealized Losses on Securities Available-for-Sale, Less than 12 Months, Fair Value	87,303	74,904
Unrealized Losses on Securities Available-for-Sale, Less than 12 Months, Gross Unrealized Losses	(1,229)	(575)
Unrealized Losses on Securities Available-for-Sale, 12 Months or Longer, Fair Value	0	0
Unrealized Losses on Securities Available-for-Sale, 12 Months or Longer, Gross Unrealized Losses	0	0
Unrealized Losses on Securities Available-for-Sale, Fair Value	87,303	74,904
Unrealized Losses on Securities Available-for-Sale, Gross Unrealized Losses	(1,229)	(575)
Asset-backed
Unrealized Losses on Securities Available-for-Sale, Less than 12 Months, Fair Value	64,382	45,198
Unrealized Losses on Securities Available-for-Sale, Less than 12 Months, Gross Unrealized Losses	(1,199)	(818)
Unrealized Losses on Securities Available-for-Sale, 12 Months or Longer, Fair Value	7,630	10,473
Unrealized Losses on Securities Available-for-Sale, 12 Months or Longer, Gross Unrealized Losses	(100)	(56)
Unrealized Losses on Securities Available-for-Sale, Fair Value	72,012	55,671
Unrealized Losses on Securities Available-for-Sale, Gross Unrealized Losses	$ (1,299)	(874)
Equity Securities
Unrealized Losses on Securities Available-for-Sale, Less than 12 Months, Fair Value		1,039
Unrealized Losses on Securities Available-for-Sale, Less than 12 Months, Gross Unrealized Losses		(130)
Unrealized Losses on Securities Available-for-Sale, 12 Months or Longer, Fair Value		0
Unrealized Losses on Securities Available-for-Sale, 12 Months or Longer, Gross Unrealized Losses		0
Unrealized Losses on Securities Available-for-Sale, Fair Value		1,039
Unrealized Losses on Securities Available-for-Sale, Gross Unrealized Losses		$ (130)