Investment Securities - Investments' Gross Unrealized Losses and Fair Value Aggregated by Investment Category and Length of Time in Continuous Unrealized Loss Position (Details) $ in Thousands	Jun. 30, 2022 USD ($) security	Dec. 31, 2021 USD ($) security
Fair Value
Less than 12 Months	$ 1,734,298	$ 636,389
12 Months or Longer	288,367	8,829
Total	2,022,665	645,218
Gross Unrealized Losses
Less than 12 Months	192,376	13,239
12 Months or Longer	56,769	401
Total	$ 249,145	$ 13,640
Number of Securities | security	1,126	161
U.S. Treasury
Fair Value
Less than 12 Months	$ 16,189	$ 999
12 Months or Longer	0	0
Total	16,189	999
Gross Unrealized Losses
Less than 12 Months	111	1
12 Months or Longer	0	0
Total	$ 111	$ 1
Number of Securities | security	3	1
U.S. Government-sponsored agency securities
Fair Value
Less than 12 Months	$ 77,942	$ 68,524
12 Months or Longer	22,208	0
Total	100,150	68,524
Gross Unrealized Losses
Less than 12 Months	6,480	1,545
12 Months or Longer	3,706	0
Total	$ 10,186	$ 1,545
Number of Securities | security	14	8
State and municipal
Fair Value
Less than 12 Months	$ 1,285,071	$ 138,187
12 Months or Longer	15,481	505
Total	1,300,552	138,692
Gross Unrealized Losses
Less than 12 Months	158,718	894
12 Months or Longer	3,972	4
Total	$ 162,690	$ 898
Number of Securities | security	936	103
U.S. Government-sponsored mortgage-backed securities
Fair Value
Less than 12 Months	$ 343,302	$ 427,687
12 Months or Longer	250,678	8,324
Total	593,980	436,011
Gross Unrealized Losses
Less than 12 Months	26,834	10,791
12 Months or Longer	49,091	397
Total	$ 75,925	$ 11,188
Number of Securities | security	164	48
Corporate obligations
Fair Value
Less than 12 Months	$ 11,794	$ 992
12 Months or Longer	0	0
Total	11,794	992
Gross Unrealized Losses
Less than 12 Months	233	8
12 Months or Longer	0	0
Total	$ 233	$ 8
Number of Securities | security	9	1