Deposits - Schedule of Composition of Deposits (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Deposit Liability [Line Items]
Customer deposits	$ 145,400	$ 146,700
Certificates of deposit with maturities within 1 year	863,300	770,700
Interest-bearing brokered money market deposits	375,500	157,200
HSA deposits	2,770,000	2,070,000
Short-term contractual deposits	4,154,200	3,144,600
Certificates of deposit with maturities greater than 1 year and less than 5 years	167,700	334,200
Total deposits	$ 4,321,900	$ 3,478,800
Weighted average cost of HSA deposits outstanding (as a percent)	0.11%	0.04%
Weighted average cost of funds on certificates of deposit outstanding (as a percent)	3.25%	1.48%
Weighted average cost of interest-bearing money market deposits outstanding (as a percent)	5.24%	4.45%
Maximum
Deposit Liability [Line Items]
Certificates of deposits denominations in dollar amount	$ 250	$ 250