Deposits - Schedule of Composition of Deposits (Details) - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Interest-bearing brokered money market deposits	$ 372,884,000	$ 362,246,000
Customer deposits	100,719,000	112,571,000
Certificates of deposit with maturities within 1 year	663,520,000	835,996,000
Short-term deposits	1,137,123,000	1,310,813,000
Certificates of deposit with maturities greater than 1 year and less than 5 years	173,399,000	143,399,000
Total deposits	$ 1,310,522,000	$ 1,454,212,000
Weighted average cost of funds on certificates of deposit outstanding (as a percent)	2.52%	2.57%
Weighted average cost of interest-bearing money market deposits (as a percent)	0.96%	1.88%
Certificates of deposits denominations in dollar amount	$ 250,000	$ 250,000
Minimum
Debt Instrument [Line Items]
Certificate of deposits maturities period	6 months	4 months
Certificate of deposits, fixed interest rates range (as a percent)	1.45%	1.80%
Maximum
Debt Instrument [Line Items]
Certificate of deposits maturities period	5 years	5 years
Certificate of deposits, fixed interest rates range (as a percent)	3.52%	3.52%