Securities - Unrealized Losses on Available-for-Sale of Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Fair Value
Less than 12 Months	$ 1,095,830	$ 417,782
12 Months or Longer	394,300	9,266
Total	1,490,130	427,048
Unrealized Losses
Less than 12 Months	20,921	3,014
12 Months or Longer	11,982	460
Total	32,903	3,474
U.S. Treasuries
Fair Value
Less than 12 Months	147,810
12 Months or Longer	0
Total	147,810
Unrealized Losses
Less than 12 Months	2,542
12 Months or Longer	0
Total	2,542
Obligations of U.S. Government sponsored entities
Fair Value
Less than 12 Months	362,895	310,711
12 Months or Longer	289,210	0
Total	652,105	310,711
Unrealized Losses
Less than 12 Months	6,694	1,992
12 Months or Longer	8,678	0
Total	15,372	1,992
Obligations of U.S. states and political subdivisions
Fair Value
Less than 12 Months	9,700	8,868
12 Months or Longer	1,283	0
Total	10,983	8,868
Unrealized Losses
Less than 12 Months	85	40
12 Months or Longer	15	0
Total	100	40
U.S. Government agencies
Fair Value
Less than 12 Months	22,074	10,560
12 Months or Longer	16,846	1,819
Total	38,920	12,379
Unrealized Losses
Less than 12 Months	160	396
12 Months or Longer	372	250
Total	532	646
U.S. Government sponsored entities
Fair Value
Less than 12 Months	553,351	87,643
12 Months or Longer	84,537	5,068
Total	637,888	92,711
Unrealized Losses
Less than 12 Months	11,440	586
12 Months or Longer	2,841	89
Total	14,281	675
U.S. corporate debt securities
Fair Value
Less than 12 Months	0	0
12 Months or Longer	2,424	2,379
Total	2,424	2,379
Unrealized Losses
Less than 12 Months	0	0
12 Months or Longer	76	121
Total	$ 76	$ 121