Fair Value Definition and Hierarchy - Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Level 1 | Carrying Amount
Financial assets:
Cash, cash equivalents and restricted cash	$ 109,756	$ 99,331
Life insurance policy benefits receivable, net	36,418	23,031
Fees receivable	31,571	29,168
Financial liabilities:
Other liabilities	57,056	44,352
Level 1 | Estimated Fair Value
Financial assets:
Cash, cash equivalents and restricted cash	109,756	99,331
Life insurance policy benefits receivable, net	36,418	23,031
Fees receivable	31,571	29,168
Financial liabilities:
Other liabilities	57,056	44,352
Level 2 | Carrying Amount
Financial assets:
Financing receivables from affiliates		67,153
Financial liabilities:
Senior credit facility	203,907	174,390
L Bonds and Seller Trust L bonds	1,521,411	1,293,530
Other borrowings	100,178	153,086
Level 2 | Estimated Fair Value
Financial assets:
Financing receivables from affiliates		59,608
Financial liabilities:
Senior credit facility	213,117	184,587
L Bonds and Seller Trust L bonds	1,638,227	1,390,288
Other borrowings	101,368	153,086
Level 3 | Carrying Amount
Financial assets:
Loans receivable, net of allowance for loan losses and discount	227,047	232,344
Level 3 | Estimated Fair Value
Financial assets:
Loans receivable, net of allowance for loan losses and discount	$ 257,764	$ 232,344