| Financing Receivable, Current, Allowance for Credit Loss [Table Text Block] |
| For the Three Months Ended June 30, | | 2026 | | | 2025 | |
| | | Notes Receivable | | | Auto Finance | | | Total | | | Notes Receivable | | | Auto Finance | | | Total | |
| Allowance for credit losses: | | | | | | | | | | | | | | | | | | | | | | | | |
| Balance at beginning of period | | $ | (8.8 | ) | | $ | (3.8 | ) | | $ | (12.6 | ) | | $ | (5.9 | ) | | $ | (4.8 | ) | | $ | (10.7 | ) |
| Provision for credit losses(1) | | | (0.4 | ) | | | (0.6 | ) | | | (1.0 | ) | | | (0.2 | ) | | | (1.2 | ) | | | (1.4 | ) |
| Charge-offs | | | — | | | | 1.3 | | | | 1.3 | | | | — | | | | 1.7 | | | | 1.7 | |
| Recoveries | | | — | | | | (0.6 | ) | | | (0.6 | ) | | | — | | | | (0.6 | ) | | | (0.6 | ) |
| Balance at end of period | | $ | (9.2 | ) | | $ | (3.7 | ) | | $ | (12.9 | ) | | $ | (6.1 | ) | | $ | (4.9 | ) | | $ | (11.0 | ) |
| For the Six Months Ended June 30, | | 2026 | | | 2025 | |
| | | Notes Receivable | | | Auto Finance | | | Total | | | Notes Receivable | | | Auto Finance | | | Total | |
| Allowance for credit losses: | | | | | | | | | | | | | | | | | | | | | | | | |
| Balance at beginning of period | | $ | (8.0 | ) | | $ | (4.1 | ) | | $ | (12.1 | ) | | $ | (5.9 | ) | | $ | (4.9 | ) | | $ | (10.8 | ) |
| Provision for credit losses(1) | | | (1.2 | ) | | | (1.4 | ) | | | (2.6 | ) | | | (0.2 | ) | | | (2.3 | ) | | | (2.5 | ) |
| Charge-offs | | | — | | | | 3.0 | | | | 3.0 | | | | — | | | | 3.5 | | | | 3.5 | |
| Recoveries | | | — | | | | (1.2 | ) | | | (1.2 | ) | | | — | | | | (1.2 | ) | | | (1.2 | ) |
| Balance at end of period | | $ | (9.2 | ) | | $ | (3.7 | ) | | $ | (12.9 | ) | | $ | (6.1 | ) | | $ | (4.9 | ) | | $ | (11.0 | ) |
| | | June 30, | | | December 31, | |
| As of | | 2026 | | | 2025 | |
| Allowance for credit losses: | | | | | | | | |
| Balance of Notes Receivable at end of period individually evaluated for impairment | | $ | (9.2 | ) | | $ | (8.0 | ) |
| Balance of Auto Finance at end of period individually evaluated for impairment | | $ | (0.5 | ) | | $ | (0.6 | ) |
| Balance of Auto Finance at end of period collectively evaluated for impairment | | $ | (3.2 | ) | | $ | (3.5 | ) |
| Loans at amortized cost: | | | | | | | | |
| Loans at amortized cost | | $ | 99.6 | | | $ | 107.1 | |
| Loans at amortized cost individually evaluated for impairment | | $ | 0.5 | | | $ | 1.1 | |
| Loans at amortized cost collectively evaluated for impairment | | $ | 99.1 | | | $ | 106.0 | |
|
| Disaggregation of Revenue [Table Text Block] |
| | | | | | | | | | | | | |
| For the Three Months Ended June 30, 2026 | | CaaS | | | Auto Finance | | | Total | |
| Interchange revenues, net (1) | | $ | 15,065 | | | $ | — | | | $ | 15,065 | |
| Servicing income | | | 11,110 | | | | 195 | | | | 11,305 | |
| Service charges and other customer related fees | | | 21,972 | | | | 8 | | | | 21,980 | |
| Total Other revenue | | | 48,147 | | | | 203 | | | | 48,350 | |
| Merchant fees (2) | | | 55,362 | | | | — | | | | 55,362 | |
| Total revenue from contracts with customers | | $ | 103,509 | | | $ | 203 | | | $ | 103,712 | |
| | | | | | | | | | | | | |
| For the Six Months Ended June 30, 2026 | | CaaS | | | Auto Finance | | | Total | |
| Interchange revenues, net (1) | | $ | 25,913 | | | $ | — | | | $ | 25,913 | |
| Servicing income | | | 19,601 | | | | 398 | | | | 19,999 | |
| Service charges and other customer related fees | | | 42,080 | | | | 18 | | | | 42,098 | |
| Total Other revenue | | | 87,594 | | | | 416 | | | | 88,010 | |
| Merchant fees (2) | | | 87,612 | | | | — | | | | 87,612 | |
| Total revenue from contracts with customers | | $ | 175,206 | | | $ | 416 | | | $ | 175,622 | |
| | | | | | | | | | | | | |
| For the Three Months Ended June 30, 2025 | | CaaS | | | Auto Finance | | | Total | |
| Interchange revenues, net (1) | | $ | 5,973 | | | $ | — | | | $ | 5,973 | |
| Servicing income | | | 5,436 | | | | 165 | | | | 5,601 | |
| Service charges and other customer related fees | | | 11,603 | | | | 8 | | | | 11,611 | |
| Total Other revenue | | | 23,012 | | | | 173 | | | | 23,185 | |
| Merchant fees (2) | | | 62,546 | | | | — | | | | 62,546 | |
| Total revenue from contracts with customers | | $ | 85,558 | | | $ | 173 | | | $ | 85,731 | |
| | | | | | | | | | | | | |
| For the Six Months Ended June 30, 2025 | | CaaS | | | Auto Finance | | | Total | |
| Interchange revenues, net (1) | | $ | 10,679 | | | $ | — | | | $ | 10,679 | |
| Servicing income | | | 9,410 | | | | 335 | | | | 9,745 | |
| Service charges and other customer related fees | | | 21,621 | | | | 17 | | | | 21,638 | |
| Total Other revenue | | | 41,710 | | | | 352 | | | | 42,062 | |
| Merchant fees (2) | | | 96,123 | | | | — | | | | 96,123 | |
| Total revenue from contracts with customers | | $ | 137,833 | | | $ | 352 | | | $ | 138,185 | |
|