Reinsurance - Narrative (Details) - USD ($) $ in Thousands		9 Months Ended
	Dec. 31, 2025	Sep. 30, 2025	Dec. 01, 2025	Dec. 31, 2024	Sep. 30, 2024	Dec. 31, 2023
Effects of Reinsurance [Line Items]
Reinsurance recoverable on loss reserves		$ 57,565		$ 47,281	$ 45,327	$ 33,302
Eligible New Insurance Written In 2026
Effects of Reinsurance [Line Items]
Reinsurance, quota share reinsurance agreement, terms, quota share, percent		40.00%
Excess of loss reinsurance coverage, initial and remaining		$ 184,000
Eligible New Insurance Written In 2027
Effects of Reinsurance [Line Items]
Reinsurance, quota share reinsurance agreement, terms, quota share, percent		40.00%
New Insurance Written In 2021 | Forecast
Effects of Reinsurance [Line Items]
Excess of loss reinsurance coverage, initial and remaining			$ 250,000
Quota Share Reinsurance Transactions
Effects of Reinsurance [Line Items]
Ceding commission, percentage (as a percent)		20.00%
Reinsurance, quote share reinsurance agreement, annual loss ratio cap (as a percent)		300.00%
Reinsurance, quota reinsurance agreement, lifetime loss ratio cap (as a percent)		200.00%
Threshold for private mortgage insurer eligibility requirements for termination election (less than) (as a percent)		90.00%
Reinsurance recoverable on loss reserves		$ 57,600		$ 47,300
Credit Union QSR Transaction
Effects of Reinsurance [Line Items]
Threshold for private mortgage insurer eligibility requirements for termination election (less than) (as a percent)		80.00%
Reinsurance, quota share reinsurance agreement, terms, quota share, percent		65.00%
2022 QSR - 2022 NIW
Effects of Reinsurance [Line Items]
Reinsurance, quota share reinsurance agreement, terms, quota share, percent		30.00%
2022 QSR - 2022 NIW | Forecast
Effects of Reinsurance [Line Items]
Reinsurance, quota share reinsurance agreement, terms, quota share, percent	28.00%
Home Re special purpose insurers
Effects of Reinsurance [Line Items]
Percent of total trust assets invested in cash or direct U.S. federal government obligations		99.50%