Investment Securities (Details 1) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Unrealized Losses on Securities Available-for-Sale, Less than 12 Months, Fair Value	$ 2,270,071	$ 1,026,780
Unrealized Losses on Securities Available-for-Sale, Less than 12 Months, Gross Unrealized Losses	(49,605)	(8,928)
Unrealized Losses on Securities Available-for-Sale, 12 Months or Longer, Fair Value	194,992	223,832
Unrealized Losses on Securities Available-for-Sale, 12 Months or Longer, Gross Unrealized Losses	(9,406)	(7,131)
Unrealized Losses on Securities Available-for-Sale, Fair Value	2,465,063	1,250,612
Unrealized Losses on Securities Available-for-Sale, Gross Unrealized Losses	(59,011)	(16,059)
Government agency and government-sponsored enterprise pass through securities
Unrealized Losses on Securities Available-for-Sale, Less than 12 Months, Fair Value	101,684	44,795
Unrealized Losses on Securities Available-for-Sale, Less than 12 Months, Gross Unrealized Losses	(1,697)	(311)
Unrealized Losses on Securities Available-for-Sale, 12 Months or Longer, Fair Value	29,300	26,010
Unrealized Losses on Securities Available-for-Sale, 12 Months or Longer, Gross Unrealized Losses	(1,096)	(533)
Unrealized Losses on Securities Available-for-Sale, Fair Value	130,984	70,805
Unrealized Losses on Securities Available-for-Sale, Gross Unrealized Losses	(2,793)	(844)
Government agency and government-sponsored enterprise collateralized mortgage obligations
Unrealized Losses on Securities Available-for-Sale, Less than 12 Months, Fair Value	464,725	163,014
Unrealized Losses on Securities Available-for-Sale, Less than 12 Months, Gross Unrealized Losses	(7,943)	(2,452)
Unrealized Losses on Securities Available-for-Sale, 12 Months or Longer, Fair Value	18,149	20,928
Unrealized Losses on Securities Available-for-Sale, 12 Months or Longer, Gross Unrealized Losses	(484)	(445)
Unrealized Losses on Securities Available-for-Sale, Fair Value	482,874	183,942
Unrealized Losses on Securities Available-for-Sale, Gross Unrealized Losses	(8,427)	(2,897)
Private label collateralized mortgage obligations
Unrealized Losses on Securities Available-for-Sale, Less than 12 Months, Fair Value	80,735	50,521
Unrealized Losses on Securities Available-for-Sale, Less than 12 Months, Gross Unrealized Losses	(1,672)	(500)
Unrealized Losses on Securities Available-for-Sale, 12 Months or Longer, Fair Value	4,172	5,035
Unrealized Losses on Securities Available-for-Sale, 12 Months or Longer, Gross Unrealized Losses	(31)	(142)
Unrealized Losses on Securities Available-for-Sale, Fair Value	84,907	55,556
Unrealized Losses on Securities Available-for-Sale, Gross Unrealized Losses	(1,703)	(642)
Municipal securities
Unrealized Losses on Securities Available-for-Sale, Less than 12 Months, Fair Value	344,023	67,936
Unrealized Losses on Securities Available-for-Sale, Less than 12 Months, Gross Unrealized Losses	(6,238)	(365)
Unrealized Losses on Securities Available-for-Sale, 12 Months or Longer, Fair Value	30,188	32,326
Unrealized Losses on Securities Available-for-Sale, 12 Months or Longer, Gross Unrealized Losses	(1,895)	(974)
Unrealized Losses on Securities Available-for-Sale, Fair Value	374,211	100,262
Unrealized Losses on Securities Available-for-Sale, Gross Unrealized Losses	(8,133)	(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	1,021,518	579,373
Unrealized Losses on Securities Available-for-Sale, Less than 12 Months, Gross Unrealized Losses	(29,290)	(3,777)
Unrealized Losses on Securities Available-for-Sale, 12 Months or Longer, Fair Value	75,698	129,060
Unrealized Losses on Securities Available-for-Sale, 12 Months or Longer, Gross Unrealized Losses	(4,795)	(4,981)
Unrealized Losses on Securities Available-for-Sale, Fair Value	1,097,216	708,433
Unrealized Losses on Securities Available-for-Sale, Gross Unrealized Losses	(34,085)	(8,758)
US Treasury Securities
Unrealized Losses on Securities Available-for-Sale, Less than 12 Months, Fair Value	147,739
Unrealized Losses on Securities Available-for-Sale, Less than 12 Months, Gross Unrealized Losses	(590)
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	147,739
Unrealized Losses on Securities Available-for-Sale, Gross Unrealized Losses	(590)
SBA asset-backed securities
Unrealized Losses on Securities Available-for-Sale, Less than 12 Months, Fair Value	63,348	74,904
Unrealized Losses on Securities Available-for-Sale, Less than 12 Months, Gross Unrealized Losses	(1,575)	(575)
Unrealized Losses on Securities Available-for-Sale, 12 Months or Longer, Fair Value	14,003	0
Unrealized Losses on Securities Available-for-Sale, 12 Months or Longer, Gross Unrealized Losses	(391)	0
Unrealized Losses on Securities Available-for-Sale, Fair Value	77,351	74,904
Unrealized Losses on Securities Available-for-Sale, Gross Unrealized Losses	(1,966)	(575)
Asset-backed
Unrealized Losses on Securities Available-for-Sale, Less than 12 Months, Fair Value	46,299	45,198
Unrealized Losses on Securities Available-for-Sale, Less than 12 Months, Gross Unrealized Losses	(600)	(818)
Unrealized Losses on Securities Available-for-Sale, 12 Months or Longer, Fair Value	23,482	10,473
Unrealized Losses on Securities Available-for-Sale, 12 Months or Longer, Gross Unrealized Losses	(714)	(56)
Unrealized Losses on Securities Available-for-Sale, Fair Value	69,781	55,671
Unrealized Losses on Securities Available-for-Sale, Gross Unrealized Losses	$ (1,314)	(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)