Investment Securities (Details 1) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Unrealized Losses on Securities Available-for-Sale, Less than 12 Months, Fair Value	$ 267,326	$ 316,746
Unrealized Losses on Securities Available-for-Sale, Less than 12 Months, Gross Unrealized Losses	(1,052)	(2,032)
Unrealized Losses on Securities Available-for-Sale, 12 Months or Longer, Fair Value	96,991	1,706,835
Unrealized Losses on Securities Available-for-Sale, 12 Months or Longer, Gross Unrealized Losses	(891)	(38,258)
Unrealized Losses on Securities Available-for-Sale, Fair Value	364,317	2,023,581
Unrealized Losses on Securities Available-for-Sale, Gross Unrealized Losses	(1,943)	(40,290)
Government agency and government-sponsored enterprise pass through securities
Unrealized Losses on Securities Available-for-Sale, Less than 12 Months, Fair Value	0	60,164
Unrealized Losses on Securities Available-for-Sale, Less than 12 Months, Gross Unrealized Losses	0	(169)
Unrealized Losses on Securities Available-for-Sale, 12 Months or Longer, Fair Value	9,533	85,245
Unrealized Losses on Securities Available-for-Sale, 12 Months or Longer, Gross Unrealized Losses	(152)	(2,131)
Unrealized Losses on Securities Available-for-Sale, Fair Value	9,533	145,409
Unrealized Losses on Securities Available-for-Sale, Gross Unrealized Losses	(152)	(2,300)
Government agency and government-sponsored enterprise collateralized mortgage obligations
Unrealized Losses on Securities Available-for-Sale, Less than 12 Months, Fair Value	85,397	69,859
Unrealized Losses on Securities Available-for-Sale, Less than 12 Months, Gross Unrealized Losses	(267)	(326)
Unrealized Losses on Securities Available-for-Sale, 12 Months or Longer, Fair Value	7,696	164,097
Unrealized Losses on Securities Available-for-Sale, 12 Months or Longer, Gross Unrealized Losses	(39)	(5,046)
Unrealized Losses on Securities Available-for-Sale, Fair Value	93,093	233,956
Unrealized Losses on Securities Available-for-Sale, Gross Unrealized Losses	(306)	(5,372)
Private label collateralized mortgage obligations
Unrealized Losses on Securities Available-for-Sale, Less than 12 Months, Fair Value	0	32,170
Unrealized Losses on Securities Available-for-Sale, Less than 12 Months, Gross Unrealized Losses	0	(831)
Unrealized Losses on Securities Available-for-Sale, 12 Months or Longer, Fair Value	18,008	49,237
Unrealized Losses on Securities Available-for-Sale, 12 Months or Longer, Gross Unrealized Losses	(99)	(1,262)
Unrealized Losses on Securities Available-for-Sale, Fair Value	18,008	81,407
Unrealized Losses on Securities Available-for-Sale, Gross Unrealized Losses	(99)	(2,093)
Collateralized loan obligations
Unrealized Losses on Securities Available-for-Sale, Less than 12 Months, Fair Value	93,802
Unrealized Losses on Securities Available-for-Sale, Less than 12 Months, Gross Unrealized Losses	(347)
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	93,802
Unrealized Losses on Securities Available-for-Sale, Gross Unrealized Losses	(347)
Municipal securities
Unrealized Losses on Securities Available-for-Sale, Less than 12 Months, Fair Value	4,044	52,386
Unrealized Losses on Securities Available-for-Sale, Less than 12 Months, Gross Unrealized Losses	(12)	(238)
Unrealized Losses on Securities Available-for-Sale, 12 Months or Longer, Fair Value	25,874	284,915
Unrealized Losses on Securities Available-for-Sale, 12 Months or Longer, Gross Unrealized Losses	(482)	(7,082)
Unrealized Losses on Securities Available-for-Sale, Fair Value	29,918	337,301
Unrealized Losses on Securities Available-for-Sale, Gross Unrealized Losses	(494)	(7,320)
Government agency and government-sponsored enterprise commercial mortgage-backed securities
Unrealized Losses on Securities Available-for-Sale, Less than 12 Months, Fair Value	0	40,641
Unrealized Losses on Securities Available-for-Sale, Less than 12 Months, Gross Unrealized Losses	0	(341)
Unrealized Losses on Securities Available-for-Sale, 12 Months or Longer, Fair Value	29,902	1,020,684
Unrealized Losses on Securities Available-for-Sale, 12 Months or Longer, Gross Unrealized Losses	(95)	(21,184)
Unrealized Losses on Securities Available-for-Sale, Fair Value	29,902	1,061,325
Unrealized Losses on Securities Available-for-Sale, Gross Unrealized Losses	(95)	(21,525)
US Treasury Securities
Unrealized Losses on Securities Available-for-Sale, Less than 12 Months, Fair Value		49,729
Unrealized Losses on Securities Available-for-Sale, Less than 12 Months, Gross Unrealized Losses		(88)
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		49,729
Unrealized Losses on Securities Available-for-Sale, Gross Unrealized Losses		(88)
Asset-backed Securities
Unrealized Losses on Securities Available-for-Sale, Less than 12 Months, Fair Value	84,083	11,548
Unrealized Losses on Securities Available-for-Sale, Less than 12 Months, Gross Unrealized Losses	(426)	(38)
Unrealized Losses on Securities Available-for-Sale, 12 Months or Longer, Fair Value	3,915	35,859
Unrealized Losses on Securities Available-for-Sale, 12 Months or Longer, Gross Unrealized Losses	(12)	(443)
Unrealized Losses on Securities Available-for-Sale, Fair Value	87,998	47,407
Unrealized Losses on Securities Available-for-Sale, Gross Unrealized Losses	(438)	(481)
SBA asset-backed securities
Unrealized Losses on Securities Available-for-Sale, Less than 12 Months, Fair Value	0	249
Unrealized Losses on Securities Available-for-Sale, Less than 12 Months, Gross Unrealized Losses	0	(1)
Unrealized Losses on Securities Available-for-Sale, 12 Months or Longer, Fair Value	2,063	66,798
Unrealized Losses on Securities Available-for-Sale, 12 Months or Longer, Gross Unrealized Losses	(12)	(1,110)
Unrealized Losses on Securities Available-for-Sale, Fair Value	2,063	67,047
Unrealized Losses on Securities Available-for-Sale, Gross Unrealized Losses	$ (12)	$ (1,111)