Accumulated Other Comprehensive Income (Loss) - Summary of Changes (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Accumulated Other Comprehensive Income (Loss)
Beginning balance	$ 1,807,633	$ 1,805,856	$ 1,912,571	$ 1,875,645
Other comprehensive income (loss) before reclassifications			(253,481)	(12,349)
Amounts reclassified from accumulated other comprehensive income			(188)	(2,407)
Total other comprehensive income (loss), net of tax	(114,164)	24,270	(253,669)	(14,756)
Ending balance	1,977,641	1,871,800	1,977,641	1,871,800
Total
Accumulated Other Comprehensive Income (Loss)
Beginning balance	(84,392)	35,810	55,113	74,836
Total other comprehensive income (loss), net of tax	(114,164)	24,270	(253,669)	(14,756)
Ending balance	(198,556)	60,080	(198,556)	60,080
Unrealized Gains (Losses) on Securities Available for Sale
Accumulated Other Comprehensive Income (Loss)
Beginning balance			59,774	87,988
Other comprehensive income (loss) before reclassifications			(253,807)	(12,382)
Amounts reclassified from accumulated other comprehensive income			(518)	(2,812)
Total other comprehensive income (loss), net of tax			(254,325)	(15,194)
Ending balance	(194,551)	72,794	(194,551)	72,794
Unrealized Gains (Losses) on Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss)
Beginning balance			(660)	(1,594)
Other comprehensive income (loss) before reclassifications			326	33
Amounts reclassified from accumulated other comprehensive income			330	405
Total other comprehensive income (loss), net of tax			656	438
Ending balance	(4)	(1,156)	(4)	(1,156)
Unrealized Gains (Losses) on Defined Benefit Plans
Accumulated Other Comprehensive Income (Loss)
Beginning balance			(4,001)	(11,558)
Other comprehensive income (loss) before reclassifications			0	0
Amounts reclassified from accumulated other comprehensive income			0	0
Total other comprehensive income (loss), net of tax			0	0
Ending balance	$ (4,001)	$ (11,558)	$ (4,001)	$ (11,558)