Deposits - Composition of Deposits (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Statistical Disclosure for Banks [Abstract]
Noninterest-bearing demand deposit accounts	$ 1,578,306	$ 1,054,458
Interest-bearing deposit accounts:
Interest-bearing demand accounts	201,510	164,870
Savings accounts and money market accounts	2,711,417	2,472,965
NOW accounts	37,888	95,297
Certificate of deposit accounts:
Less than $100	151,696	164,491
$100 through $250	104,864	113,006
Greater than $250	72,304	88,462
Total interest-bearing deposit accounts	3,279,679	3,099,091
Total deposits	$ 4,857,985	$ 4,153,549