Loans to Bank Customers - Credit Quality Indicators (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Non-Classified
Outstanding Loans [Line Items]
Total loans	$ 20,028	$ 19,921
Classified
Outstanding Loans [Line Items]
Total loans	1,740	2,662
Residential | Non-Classified
Outstanding Loans [Line Items]
Total loans	2,768	4,241
Residential | Classified
Outstanding Loans [Line Items]
Total loans	240	290
Commercial | Non-Classified
Outstanding Loans [Line Items]
Total loans	3,435	158
Commercial | Classified
Outstanding Loans [Line Items]
Total loans	0	0
Installment | Non-Classified
Outstanding Loans [Line Items]
Total loans	360	1,058
Installment | Classified
Outstanding Loans [Line Items]
Total loans	137	189
Secured credit card | Non-Classified
Outstanding Loans [Line Items]
Total loans	13,465	14,464
Secured credit card | Classified
Outstanding Loans [Line Items]
Total loans	$ 1,363	$ 2,183