Reserve for Losses and Loss Adjustment Expenses - Summary of Incurred Losses and Allocated Loss Adjustment Expense (Details) $ in Thousands	Dec. 31, 2020 USD ($) loan	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)	Dec. 31, 2012 USD ($)	Dec. 31, 2011 USD ($)
Liability for Claims and Claims Adjustment Expense [Line Items]
Cumulative paid losses and allocated LAE for the years ended December 31	$ 54,788
All outstanding liabilities before 2011, net of reinsurance	0
Reserve for losses and LAE, net of reinsurance	355,880	$ 69,291	$ 49,464	$ 46,850
Less: Reinsurance recoverables	19,061	71	0	0
Total gross reserve for losses and LAE	374,941	69,362	49,464	46,850
Property Insurance Product Line
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred loss and allocated LAE, for the years ended December 31	410,668
2011 | Property Insurance Product Line
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred loss and allocated LAE, for the years ended December 31	0	0	0	0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 57
Total of IBNR plus expected development on reported defaults	$ 0
Cumulative number of reported defaults | loan	1
Cumulative paid losses and allocated LAE for the years ended December 31	$ 0	0	0	0	0	0	0	0	0	$ 0
2012 | Property Insurance Product Line
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred loss and allocated LAE, for the years ended December 31	808	808	808	809	748	781	814	858	1,523
Total of IBNR plus expected development on reported defaults	$ 0
Cumulative number of reported defaults | loan	19
Cumulative paid losses and allocated LAE for the years ended December 31	$ 808	808	808	808	665	665	659	535	$ 24
2013 | Property Insurance Product Line
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred loss and allocated LAE, for the years ended December 31	2,058	2,058	2,058	2,060	1,997	2,008	2,461	2,986
Total of IBNR plus expected development on reported defaults	$ 0
Cumulative number of reported defaults | loan	51
Cumulative paid losses and allocated LAE for the years ended December 31	$ 2,058	2,058	2,058	1,880	1,775	1,501	928	$ 239
2014 | Property Insurance Product Line
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred loss and allocated LAE, for the years ended December 31	2,882	2,897	2,930	2,984	3,323	4,312	6,877
Total of IBNR plus expected development on reported defaults	$ 1
Cumulative number of reported defaults | loan	92
Cumulative paid losses and allocated LAE for the years ended December 31	$ 2,867	2,882	2,897	2,787	2,463	1,587	$ 138
2015 | Property Insurance Product Line
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred loss and allocated LAE, for the years ended December 31	8,323	8,461	8,439	8,893	9,625	14,956
Total of IBNR plus expected development on reported defaults	$ 18
Cumulative number of reported defaults | loan	214
Cumulative paid losses and allocated LAE for the years ended December 31	$ 8,055	7,961	7,535	6,960	3,610	$ 544
2016 | Property Insurance Product Line
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred loss and allocated LAE, for the years ended December 31	8,972	9,219	9,455	11,890	21,889
Total of IBNR plus expected development on reported defaults	$ 45
Cumulative number of reported defaults | loan	252
Cumulative paid losses and allocated LAE for the years ended December 31	$ 8,270	7,864	6,947	4,896	$ 927
2017 | Property Insurance Product Line
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred loss and allocated LAE, for the years ended December 31	11,488	12,202	16,261	38,178
Total of IBNR plus expected development on reported defaults	$ 85
Cumulative number of reported defaults | loan	365
Cumulative paid losses and allocated LAE for the years ended December 31	$ 10,257	9,156	5,370	$ 633
2018 | Property Insurance Product Line
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred loss and allocated LAE, for the years ended December 31	19,536	23,168	36,438
Total of IBNR plus expected development on reported defaults	$ 424
Cumulative number of reported defaults | loan	606
Cumulative paid losses and allocated LAE for the years ended December 31	$ 13,406	8,067	$ 1,310
2019 | Property Insurance Product Line
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred loss and allocated LAE, for the years ended December 31	39,085	50,562
Total of IBNR plus expected development on reported defaults	$ 2,151
Cumulative number of reported defaults | loan	1,551
Cumulative paid losses and allocated LAE for the years ended December 31	$ 8,049	$ 1,288
2020 | Property Insurance Product Line
Liability for Claims and Claims Adjustment Expense [Line Items]
Incurred loss and allocated LAE, for the years ended December 31	317,516
Total of IBNR plus expected development on reported defaults	$ 23,023
Cumulative number of reported defaults | loan	29,834
Cumulative paid losses and allocated LAE for the years ended December 31	$ 1,018