Reinsurance - Excess of Loss Reinsurance (Details) $ in Thousands									9 Months Ended	12 Months Ended
	Apr. 01, 2024 USD ($)	Oct. 23, 2023 USD ($)	Apr. 01, 2023 USD ($)	Apr. 26, 2022 USD ($)	Apr. 01, 2022 USD ($)	Aug. 03, 2021 USD ($)	Feb. 02, 2021 USD ($)	May 25, 2019 USD ($)	Sep. 30, 2024 USD ($)	Dec. 31, 2023 USD ($)
2024 Traditional XOL
Effects of Reinsurance [Line Items]
Amortization period excess of loss reinsurance coverage	10 years
Excess of loss reinsurance coverage, initial and remaining	$ 187,000
2023 Traditional XOL
Effects of Reinsurance [Line Items]
Amortization period excess of loss reinsurance coverage			10 years
Excess of loss reinsurance coverage, initial and remaining			$ 96,942						$ 92,768	$ 96,942
Initial First Layer Retention			$ 70,578
Remaining First Layer Retention									70,516	70,578
2022 Traditional XOL
Effects of Reinsurance [Line Items]
Amortization period excess of loss reinsurance coverage					10 years
Excess of loss reinsurance coverage, initial and remaining					$ 142,642				129,315	142,642
Initial First Layer Retention					$ 82,523
Remaining First Layer Retention									$ 81,653	82,346
Excess of Loss Reinsurance Transactions, Home Re Transactions
Effects of Reinsurance [Line Items]
Percent of reinsurance coverage threshold, option to terminate (as a percent)									10.00%
Home Re 2023-1
Effects of Reinsurance [Line Items]
Term of mortgage insurance-linked notes		10 years
Excess of loss reinsurance coverage, initial and remaining		$ 330,277							$ 316,783	330,277
Initial First Layer Retention		$ 272,961
Remaining First Layer Retention									$ 272,633	272,961
Reinsurance Retention Policy, Funding Percentage		0.97							0.97
Home Re 2022-1
Effects of Reinsurance [Line Items]
Term of mortgage insurance-linked notes				12 years 6 months
Excess of loss reinsurance coverage, initial and remaining				$ 473,575					$ 330,904	420,731
Initial First Layer Retention				$ 325,589
Remaining First Layer Retention									$ 323,269	325,001
Reinsurance Retention Policy, Funding Percentage				1					1
Home Re 2021-2
Effects of Reinsurance [Line Items]
Term of mortgage insurance-linked notes						12 years 6 months
Excess of loss reinsurance coverage, initial and remaining						$ 398,429			$ 145,737	173,960
Initial First Layer Retention						$ 190,159
Remaining First Layer Retention									$ 188,803	189,403
Reinsurance Retention Policy, Funding Percentage						1			0.82
Home Re 2021-1
Effects of Reinsurance [Line Items]
Term of mortgage insurance-linked notes							12 years 6 months
Excess of loss reinsurance coverage, initial and remaining							$ 398,848		$ 110,373	117,982
Initial First Layer Retention							$ 211,159
Remaining First Layer Retention									$ 210,303	210,831
Reinsurance Retention Policy, Funding Percentage							1		1
Home Re 2019-1
Effects of Reinsurance [Line Items]
Term of mortgage insurance-linked notes								10 years
Excess of loss reinsurance coverage, initial and remaining								$ 315,739	$ 21,039	21,039
Initial First Layer Retention								$ 185,730
Remaining First Layer Retention									$ 182,220	$ 182,722
Reinsurance Retention Policy, Funding Percentage								1	0.10