Summary of Significant Accounting Policies - Schedule of Accumulated Other Comprehensive Income, Net of Tax (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2021	Jun. 30, 2020
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ 1,077,492	$ 992,477	$ 693,617	$ 799,276	$ 992,477	$ 799,276
Other comprehensive (loss)/income before reclassifications	(34,321)		31,454		32,452	(68,898)
Amounts reclassified from AOCI	(690)		(1,514)		(1,796)	(6,438)
Other comprehensive (loss)/income net of tax	(35,011)	65,667	29,940	(105,276)	30,656	(75,336)
Ending balance	1,180,215	1,077,492	824,116	693,617	1,180,215	824,116
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	38,491	(13,937)	(121,858)	(43,397)	(13,937)	(43,397)
Other comprehensive (loss)/income before reclassifications	(28,751)		34,374		24,459	(43,310)
Amounts reclassified from AOCI	(786)		(777)		(1,568)	(1,554)
Other comprehensive (loss)/income net of tax	(29,537)		33,597		22,891	(44,864)
Ending balance	8,954	38,491	(88,261)	(121,858)	8,954	(88,261)
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	21,125	22,829	28,351	32,845	22,829	32,845
Other comprehensive (loss)/income before reclassifications	0		0		0	0
Amounts reclassified from AOCI	(1,306)		(1,972)		(3,010)	(6,466)
Other comprehensive (loss)/income net of tax	(1,306)		(1,972)		(3,010)	(6,466)
Ending balance	19,819	21,125	26,379	28,351	19,819	26,379
Cash Flow Hedges
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(7,872)	(22,815)	(27,930)	(5,609)	(22,815)	(5,609)
Other comprehensive (loss)/income before reclassifications	(5,570)		(2,920)		7,993	(25,588)
Amounts reclassified from AOCI	1,402		1,235		2,782	1,582
Other comprehensive (loss)/income net of tax	(4,168)		(1,685)		10,775	(24,006)
Ending balance	(12,040)	(7,872)	(29,615)	(27,930)	(12,040)	(29,615)
Accumulated Other Comprehensive Income (Loss)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	51,744	(13,923)	(121,437)	(16,161)	(13,923)	(16,161)
Other comprehensive (loss)/income net of tax	(35,011)	65,667	29,940	(105,276)
Ending balance	$ 16,733	$ 51,744	$ (91,497)	$ (121,437)	$ 16,733	$ (91,497)