Accumulated Other Comprehensive Income - Changes in Accumulated Other Comprehensive Income After-tax By Component (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ 846,436	$ 797,835	$ 867,185	$ 603,804
Ending balance	867,963	825,501	867,963	825,501
Net Unrealized Gain (Loss) on Available-for-Sale Debt Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	25,538	2,675	14,977	(9,047)
Net change	10,984	12,842	21,545	24,564
Ending balance	27,872	15,517	27,872	15,517
Debt Securities, Held-to-maturity, Transfer, Derivative Hedge, Gain (Loss)	(8,650)		(8,650)
Unamortized Gain (Loss) on Held-to-Maturity Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	4,778	(233)	4,934	(235)
Net change	(329)	3	(485)	5
Ending balance	13,099	(230)	13,099	(230)
Debt Securities, Held-to-maturity, Transfer, Derivative Hedge, Gain (Loss)	8,650		8,650
Net Unrealized Loss on Cash Flow Hedges
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(7,219)	(952)	(2,162)	0
Net change	(943)	(1,261)	(6,000)	(2,213)
Ending balance	(8,162)	(2,213)	(8,162)	(2,213)
Debt Securities, Held-to-maturity, Transfer, Derivative Hedge, Gain (Loss)	0		0
Total
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	23,097	1,490	17,749	(9,282)
Net change	9,712	11,584	15,060	22,356
Ending balance	32,809	$ 13,074	32,809	$ 13,074
Debt Securities, Held-to-maturity, Transfer, Derivative Hedge, Gain (Loss)	$ 0		$ 0