Other Comprehensive Income - Schedule of Changes in Accumulated Other Comprehensive Loss after Tax (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ 4,384,188	$ 3,350,454	$ 2,533,165
Other comprehensive income (loss) before reclassifications	22,176	35,712	(28,209)
Amounts reclassified from other comprehensive income (loss)	2,320	1,505	5,324
Other comprehensive income (loss), net	24,496	37,217	(22,885)
Ending balance	4,592,120	4,384,188	3,350,454
Cumulative Effect, Period of Adoption, Adjustment
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(28,187)
Ending balance		(28,187)
Cumulative Effect, Period of Adoption, Adjusted Balance
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	4,356,001	3,353,422	2,515,554
Ending balance		4,356,001	3,353,422
Total Accumulated Other Comprehensive Loss
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(32,214)	(69,431)	(46,005)
Ending balance	(7,718)	(32,214)	(69,431)
Total Accumulated Other Comprehensive Loss | Cumulative Effect, Period of Adoption, Adjusted Balance
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(32,214)	(69,431)	(46,546)
Ending balance		(32,214)	(69,431)
Unrealized Gains and Losses on AFS Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	5,822	(33,559)	(12,384)
Other comprehensive income (loss) before reclassifications	27,845	39,262	(22,932)
Amounts reclassified from other comprehensive income (loss)	(377)	119	2,237
Other comprehensive income (loss), net	27,468	39,381	(20,695)
Ending balance	33,290	5,822	(33,559)
Unrealized Gains and Losses on AFS Securities | Cumulative Effect, Period of Adoption, Adjusted Balance
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance			(12,864)
Unrealized Gains and Losses on Derivatives
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(3,729)	(4,031)	(8,338)
Other comprehensive income (loss) before reclassifications	(2,251)	(989)	1,874
Amounts reclassified from other comprehensive income (loss)	2,074	1,291	2,494
Other comprehensive income (loss), net	(177)	302	4,368
Ending balance	(3,906)	(3,729)	(4,031)
Unrealized Gains and Losses on Derivatives | Cumulative Effect, Period of Adoption, Adjusted Balance
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance			(8,399)
Defined Benefit Pension Plan
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(34,307)	(31,841)	(25,283)
Other comprehensive income (loss) before reclassifications	(3,418)	(2,561)	(7,151)
Amounts reclassified from other comprehensive income (loss)	623	95	593
Other comprehensive income (loss), net	(2,795)	(2,466)	(6,558)
Ending balance	$ (37,102)	$ (34,307)	(31,841)
Defined Benefit Pension Plan | Cumulative Effect, Period of Adoption, Adjusted Balance
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance			(25,283)
ASU 2016-01 | Total Accumulated Other Comprehensive Loss | Cumulative Effect, Period of Adoption, Adjustment
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance			(480)
ASU 2016-01 | Unrealized Gains and Losses on AFS Securities | Cumulative Effect, Period of Adoption, Adjustment
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance			(480)
ASU 2016-01 | Unrealized Gains and Losses on Derivatives | Cumulative Effect, Period of Adoption, Adjustment
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance			0
ASU 2016-01 | Defined Benefit Pension Plan | Cumulative Effect, Period of Adoption, Adjustment
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance			0
ASU 2017-12 | Total Accumulated Other Comprehensive Loss | Cumulative Effect, Period of Adoption, Adjustment
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance			(61)
ASU 2017-12 | Unrealized Gains and Losses on AFS Securities | Cumulative Effect, Period of Adoption, Adjustment
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance			0
ASU 2017-12 | Unrealized Gains and Losses on Derivatives | Cumulative Effect, Period of Adoption, Adjustment
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance			(61)
ASU 2017-12 | Defined Benefit Pension Plan | Cumulative Effect, Period of Adoption, Adjustment
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance			$ 0