Accumulated Other Comprehensive Income - Changes in Accumulated Other Comprehensive Income After-tax By Component (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ 867,963	$ 825,501	$ 867,185	$ 603,804
Ending balance	882,267	846,095	882,267	846,095
Net Unrealized Gain (Loss) on Available-for-Sale Debt Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	27,872	15,517	14,977	(9,047)
Net change	(220)	6,764	21,325	31,328
Ending balance	27,652	22,281	27,652	22,281
Debt Securities, Held-to-maturity, Transfer, Derivative Hedge, Gain (Loss)			(8,650)
Unamortized Gain (Loss) on Held-to-Maturity Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	13,099	(230)	4,934	(235)
Net change	(705)	10	(1,190)	15
Ending balance	12,394	(220)	12,394	(220)
Debt Securities, Held-to-maturity, Transfer, Derivative Hedge, Gain (Loss)			8,650
Net Unrealized Loss on Cash Flow Hedges
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(8,162)	(2,213)	(2,162)	0
Net change	624	(637)	(5,376)	(2,850)
Ending balance	(7,538)	(2,850)	(7,538)	(2,850)
Debt Securities, Held-to-maturity, Transfer, Derivative Hedge, Gain (Loss)			0
Total
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	32,809	13,074	17,749	(9,282)
Net change	(301)	6,137	14,759	28,493
Ending balance	$ 32,508	$ 19,211	32,508	$ 19,211
Debt Securities, Held-to-maturity, Transfer, Derivative Hedge, Gain (Loss)			$ 0