Reserve for Losses and Loss Adjustment Expenses - Reconciliation of Reserve Balances for Losses and Loss Adjustment Expense (Details) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020 USD ($) loan	Sep. 30, 2020 USD ($)	Jun. 30, 2020 USD ($)	Mar. 31, 2020 USD ($)	Dec. 31, 2019 USD ($) loan	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2020 USD ($) loan	Dec. 31, 2019 USD ($) loan	Dec. 31, 2018 USD ($) loan	Dec. 31, 2017 USD ($)
Reconciliation of the beginning and ending reserve balances for losses and loss adjustment expenses (LAE)
Reserve for losses and LAE at beginning of year				$ 69,362				$ 49,464	$ 69,362	$ 49,464	$ 46,850
Less: Reinsurance recoverables	$ 19,061				$ 71				19,061	71	0	$ 0
Net reserve for losses and LAE at beginning of year				69,291				49,464	69,291	49,464	46,850
Add provision for losses and LAE, net of reinsurance, occurring in:
Current year									317,516	50,562	36,438
Prior years									(16,223)	(17,576)	(24,863)
Net incurred losses and LAE during the current year	62,073	$ 55,280	$ 175,877	$ 8,063	10,929	$ 9,990	$ 4,960	$ 7,107	301,293	32,986	11,575
Deduct payments for losses and LAE, net of reinsurance, occurring in:
Current year									1,018	1,288	1,310
Prior years									13,686	11,871	7,651
Net loss and LAE payments during the current year									14,704	13,159	8,961
Net reserve for losses and LAE at end of year	355,880				69,291				355,880	69,291	49,464
Plus: Reinsurance recoverables	19,061				71				19,061	71	0	$ 0
Reserve for losses and LAE at end of year	$ 374,941				$ 69,362				$ 374,941	$ 69,362	$ 49,464
Loans in default at end of year | loan	31,469				5,947				31,469	5,947	4,024