Finance Receivables - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Receivables past due and accruing interest	$ 33,079	$ 48,026	$ 42,336	$ 40,076	$ 40,725
Retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
Approved but unfunded retail loans	$ 134,900	160,400
Threshold period past due to be charged-off	120 days
Reversal of accrued interest against interest income	$ 19,100
Receivables past due and accruing interest	33,100	48,000
Wholesale
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unused lines of credit, wholesale	1,640,000	1,140,000
Reversal of accrued interest against interest income	$ 400
Financing receivable on non-accrual status		5,000
Wholesale | Greater than 90 days past due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Receivables past due and accruing interest		$ 2,600
Texas | Finance receivables | Geographic Concentration Risk
Accounts, Notes, Loans and Financing Receivable [Line Items]
Concentration risk (as a percent)	11.00%	11.00%