Summary of Significant Accounting Policies - Schedule of Accumulated Other Comprehensive Income, Net of Tax (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2019
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ 992,477	$ 799,276
Other comprehensive income/(loss) before reclassifications		(100,353)	$ 66,773
Amounts reclassified from AOCI		(4,923)	(1,106)
Other comprehensive income/(loss) net of tax	65,667	(105,276)	65,667
Ending balance	1,077,492	693,617
Accumulated Net Investment Gain (Loss) Including Portion Attributable to Noncontrolling Interest | Available-for-Sale Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(13,937)	(43,397)
Other comprehensive income/(loss) before reclassifications	53,211	(77,685)
Amounts reclassified from AOCI	(783)	(776)
Other comprehensive income/(loss) net of tax		(78,461)	52,428
Ending balance	38,491	(121,858)
Accumulated Net Investment Gain (Loss) Including Portion Attributable to Noncontrolling Interest | Held-to-Maturity Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	22,829	32,845
Other comprehensive income/(loss) before reclassifications	0	0
Amounts reclassified from AOCI	(1,704)	(4,494)
Other comprehensive income/(loss) net of tax		(4,494)	(1,704)
Ending balance	21,125	28,351
Cash Flow Hedges
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(22,815)	(5,609)
Other comprehensive income/(loss) before reclassifications	13,562	(22,668)
Amounts reclassified from AOCI	1,381	347
Other comprehensive income/(loss) net of tax		(22,321)	$ 14,943
Ending balance	(7,872)	(27,930)
Accumulated Other Comprehensive Income (Loss)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(13,923)	(16,161)
Other comprehensive income/(loss) net of tax	65,667	(105,276)
Ending balance	$ 51,744	$ (121,437)