Segment Reporting - Revenue and Other Segment Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Net premiums earned	$ 919,578	$ 981,131	$ 1,037,183
Total services revenue	46,092	92,216	125,825
Net investment income	258,430	195,658	147,909
Net gains (losses) on investments and other financial instruments	10,241	(80,733)	15,603
Other income	6,247	2,454	3,412
Total revenues	1,240,588	1,190,726	1,329,932
Interest expense	89,695	84,454	84,344
Allocation of corporate operating expenses	163,858	163,000	147,386
Operating Segments
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Net premiums earned	919,578	981,131	1,037,183
Total services revenue	46,482	92,548	125,952
Net investment income	197,108	171,950	133,287
Net gains (losses) on investments and other financial instruments	0	0	1,509
Other income	5,372	2,546	2,678
Total revenues	1,168,540	1,248,175	1,300,609
Interest expense	86,188	84,440	84,344
Direct depreciation expense	10,727	11,524	12,032
Allocation of corporate operating expenses	159,366	161,422	145,964
All Other
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Net premiums earned	0	0	0
Total services revenue	0	0	154
Net investment income	61,322	23,708	14,622
Net gains (losses) on investments and other financial instruments	814	47	0
Other income	27	78	734
Total revenues	62,163	23,833	15,510
Inter-segment
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Net premiums earned	0	0	0
Total services revenue	(390)	(332)	(281)
Net investment income	0	0	0
Net gains (losses) on investments and other financial instruments	0	0	0
Other income	(20)	(170)	0
Total revenues	(410)	(502)	(281)
Adjustments
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Net premiums earned	0	0	0
Total services revenue	0	0	0
Net investment income	0	0	0
Net gains (losses) on investments and other financial instruments	9,427	(80,780)	14,094
Other income	868	0	0
Total revenues	10,295	(80,780)	14,094
Mortgage Insurance | Operating Segments
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Net premiums earned	909,363	957,213	998,282
Total services revenue	1,088	7,390	17,670
Net investment income	195,077	171,221	132,929
Net gains (losses) on investments and other financial instruments	0	0	0
Other income	5,372	2,376	2,678
Total revenues	1,110,900	1,138,200	1,151,559
Interest expense	86,188	84,440	84,344
Direct depreciation expense	8,164	8,986	9,580
Allocation of corporate operating expenses	140,583	138,566	127,482
homegenius | Operating Segments
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Net premiums earned	10,215	23,918	38,901
Total services revenue	45,394	85,158	108,282
Net investment income	2,031	729	358
Net gains (losses) on investments and other financial instruments	0	0	1,509
Other income	0	170	0
Total revenues	57,640	109,975	149,050
Interest expense	0	0	0
Direct depreciation expense	2,563	2,538	2,452
Allocation of corporate operating expenses	$ 18,783	$ 22,856	$ 18,482