Deposits - Composition of Deposits (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Deposits [Abstract]
Non-interest-bearing demand deposits	$ 1,718,682	$ 1,279,641
Interest-bearing checking accounts	584,682	338,185
Money market demand accounts	1,153,433	881,387
Other savings	542,741	475,839
Time deposits (below $250,000)	622,328	916,723
Time deposits ($250,000 and above)	188,379	255,802
Total deposits	$ 4,810,245	$ 4,147,577