Securities - Schedule of Unrealized Loss and Fair Value on Investments (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Fair Value
Less Than 12 Months	$ 636,077	$ 332,099
12 Months or Longer	15,828	73,338
Total	651,905	405,437
Unrealized Losses
Less Than 12 Months	(6,169)	(1,530)
12 Months or Longer	(122)	(568)
Total	(6,291)	(2,098)
U.S. Treasury securities and obligations of U.S. government agencies
Fair Value
Less Than 12 Months	0	0
12 Months or Longer	251	256
Total	251	256
Unrealized Losses
Less Than 12 Months	0	0
12 Months or Longer	(2)	(1)
Total	(2)	(1)
Mortgage-backed securities and collateralized mortgage obligations of U.S. government-sponsored entities
Fair Value
Less Than 12 Months	538,907	203,405
12 Months or Longer	4,389	569
Total	543,296	203,974
Unrealized Losses
Less Than 12 Months	(5,866)	(1,218)
12 Months or Longer	(40)	(22)
Total	(5,906)	(1,240)
Private mortgage-backed securities and collateralized mortgage obligations
Fair Value
Less Than 12 Months	14,979	23,997
12 Months or Longer	1,738	0
Total	16,717	23,997
Unrealized Losses
Less Than 12 Months	(195)	(210)
12 Months or Longer	(23)	0
Total	(218)	(210)
Collateralized loan obligations
Fair Value
Less Than 12 Months	82,191	104,697
12 Months or Longer	9,450	72,513
Total	91,641	177,210
Unrealized Losses
Less Than 12 Months	(108)	(102)
12 Months or Longer	(57)	(545)
Total	$ (165)	$ (647)