Securities - Schedule of Unrealized Loss and Fair Value on Investments (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Fair Value
Less Than 12 Months	$ 248,995	$ 478,423
12 Months or Longer	277,801	646,354
Total	526,796	1,124,777
Unrealized Losses
Less Than 12 Months	(876)	(7,140)
12 Months or Longer	(3,745)	(19,538)
Total	(4,621)	(26,678)
U.S. Treasury securities and obligations of U.S. Government Sponsored Entities
Fair Value
Less Than 12 Months		99
12 Months or Longer		642
Total		741
Unrealized Losses
Less Than 12 Months		(1)
12 Months or Longer		(5)
Total		(6)
Mortgage-backed securities and collateralized mortgage obligations of U.S. Government Sponsored Entities
Fair Value
Less Than 12 Months	54,200	200,184
12 Months or Longer	221,222	623,420
Total	275,422	823,604
Unrealized Losses
Less Than 12 Months	(236)	(2,235)
12 Months or Longer	(3,136)	(19,136)
Total	(3,372)	(21,371)
Private mortgage-backed securities and collateralized mortgage obligations
Fair Value
Less Than 12 Months	11,343	20,071
12 Months or Longer	0	12,739
Total	11,343	32,810
Unrealized Losses
Less Than 12 Months	(5)	(344)
12 Months or Longer	0	(187)
Total	(5)	(531)
Collateralized loan obligations
Fair Value
Less Than 12 Months	183,452	238,894
12 Months or Longer	53,002	0
Total	236,454	238,894
Unrealized Losses
Less Than 12 Months	(635)	(4,319)
12 Months or Longer	(498)	0
Total	(1,133)	(4,319)
Obligations of state and political subdivisions
Fair Value
Less Than 12 Months	0	19,175
12 Months or Longer	3,577	9,553
Total	3,577	28,728
Unrealized Losses
Less Than 12 Months	0	(241)
12 Months or Longer	(111)	(210)
Total	$ (111)	$ (451)