Loans to Bank Customers - Credit Quality Indicators (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Outstanding Loans [Line Items]
Nonperforming loans	$ 19,551	$ 21,417
Non-Classified
Outstanding Loans [Line Items]
Nonperforming loans	18,945	19,921
Classified
Outstanding Loans [Line Items]
Nonperforming loans	1,176	2,662
Residential | Non-Classified
Outstanding Loans [Line Items]
Nonperforming loans	3,508	4,241
Residential | Classified
Outstanding Loans [Line Items]
Nonperforming loans	262	290
Commercial | Non-Classified
Outstanding Loans [Line Items]
Nonperforming loans	1,074	158
Commercial | Classified
Outstanding Loans [Line Items]
Nonperforming loans	0	0
Installment | Non-Classified
Outstanding Loans [Line Items]
Nonperforming loans	1,062	1,058
Installment | Classified
Outstanding Loans [Line Items]
Nonperforming loans	155	189
Secured credit card | Non-Classified
Outstanding Loans [Line Items]
Nonperforming loans	13,301	14,464
Secured credit card | Classified
Outstanding Loans [Line Items]
Nonperforming loans	$ 759	$ 2,183