Reinsurance - Excess of Loss Reinsurance (Details) $ in Thousands										3 Months Ended	12 Months Ended
	Oct. 23, 2023 USD ($)	Apr. 01, 2023 USD ($)	Apr. 26, 2022 USD ($)	Apr. 01, 2022 USD ($)	Aug. 03, 2021 USD ($)	Feb. 02, 2021 USD ($)	Oct. 29, 2020 USD ($)	May 25, 2019 USD ($)	Oct. 30, 2018 USD ($)	Mar. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)
2023 Traditional XOL
Effects of Reinsurance [Line Items]
Amortization period excess of loss reinsurance coverage		10 years
Initial first layer retention		$ 70,578
Remaining first layer retention										$ 70,572	$ 70,578
Remaining Excess of Loss Reinsurance Coverage (1)		$ 96,942								95,178	96,942
2022 Traditional XOL
Effects of Reinsurance [Line Items]
Amortization period excess of loss reinsurance coverage				10 years
Initial first layer retention				$ 82,523
Remaining first layer retention										82,241	82,346
Remaining Excess of Loss Reinsurance Coverage (1)				$ 142,642						142,642	142,642
Home Re 2023-1
Effects of Reinsurance [Line Items]
Term of mortgage insurance-linked notes	10 years
Initial first layer retention	$ 272,961
Remaining first layer retention										272,961	272,961
Remaining Excess of Loss Reinsurance Coverage (1)	$ 330,277									$ 330,277	330,277
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
Initial first layer retention			$ 325,589
Remaining first layer retention										$ 324,441	325,001
Remaining Excess of Loss Reinsurance Coverage (1)			$ 473,575							$ 398,112	420,731
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
Initial first layer retention					$ 190,159
Remaining first layer retention										$ 189,347	189,403
Remaining Excess of Loss Reinsurance Coverage (1)					$ 398,429					$ 172,395	173,960
Reinsurance Retention Policy, Funding Percentage					1					0.75
Home Re 2021-1
Effects of Reinsurance [Line Items]
Term of mortgage insurance-linked notes						12 years 6 months
Initial first layer retention						$ 211,159
Remaining first layer retention										$ 210,546	210,831
Remaining Excess of Loss Reinsurance Coverage (1)						$ 398,848				$ 117,880	117,982
Reinsurance Retention Policy, Funding Percentage						1				0.73
Home Re 2020-1
Effects of Reinsurance [Line Items]
Initial first layer retention							$ 275,283
Remaining first layer retention										$ 0	261,280
Remaining Excess of Loss Reinsurance Coverage (1)							$ 412,917			$ 0	41,846
Reinsurance Retention Policy, Funding Percentage							1			0
Home Re 2019-1
Effects of Reinsurance [Line Items]
Term of mortgage insurance-linked notes								10 years
Initial first layer retention								$ 185,730
Remaining first layer retention										$ 182,563	182,722
Remaining Excess of Loss Reinsurance Coverage (1)								$ 315,739		$ 21,039	21,039
Reinsurance Retention Policy, Funding Percentage								1		0.10
Home Re 2018-1
Effects of Reinsurance [Line Items]
Term of mortgage insurance-linked notes									10 years
Initial first layer retention									$ 168,691
Remaining first layer retention										$ 164,220	164,335
Remaining Excess of Loss Reinsurance Coverage (1)									$ 318,636	$ 58,378	$ 69,762
Reinsurance Retention Policy, Funding Percentage									1	1