Deposit Accounts - Interest expense on deposit accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Interest expense on deposit accounts
Checking accounts	$ 2,340	$ 1,167	$ 365
Money market accounts	28,279	19,567	6,720
Savings	382	357	251
Certificates of deposit accounts	27,296	16,562	6,035
Total	58,297	37,653	$ 13,371
Accrued interest on deposits	$ 590	$ 1,700