Subsequent Events - Narrative (Details) - Subsequent Event - USD ($)	May 07, 2019	Apr. 19, 2019
Class A Common Stock | Contribution Agreement | Chief Executive Officer
Subsequent Event [Line Items]
Stock contribution commitment (in shares)	43,230
Contribution of Class A common stock from related party, fee charged	$ 0
Loan And Security Agreement | Revolving Credit Facility | Line of Credit | Financing Partner
Subsequent Event [Line Items]
Agreement to provide revolving credit facility		$ 300,000,000.0
Amended and Restated Loan And Security Agreement | Revolving Credit Facility | Line of Credit | Financing Partner
Subsequent Event [Line Items]
Agreement to provide revolving credit facility	$ 350,000,000.0
Consumer Loan | MPSA
Subsequent Event [Line Items]
Commitment of purchaser, current availability financing, principal balances of finance receivables (up to)		$ 1,000,000,000.0