Background and Business Description - Additional Information (Detail)		12 Months Ended
	Apr. 29, 1991	Dec. 31, 2022 USD ($) $ / shares shares	Dec. 31, 2021 USD ($) shares	Dec. 31, 2020 USD ($)	Dec. 31, 2016	Jul. 06, 2021 USD ($)	Feb. 12, 2018 USD ($)	May 01, 2013 $ / shares	Apr. 30, 2013 $ / shares
Background And Basis Of Presentation [Line Items]
Entity Incorporation, Date of Incorporation	Apr. 29, 1991
Tier 2 Note Security in RMBS Litigation Settlement Proceeds							$ 1,600,000,000
Common stock, shares authorized | shares		130,000,000	130,000,000
Common Stock, Par or Stated Value Per Share | $ / shares									$ 0.01
Preferred stock, shares authorized | shares		20,000,000	20,000,000
Preferred Stock, Par or Stated Value Per Share | $ / shares		$ 0.01							$ 0.01
Common stock, shares issued | shares		46,658,990	46,477,068
Class of Warrant or Right, Exercise Price of Warrants or Rights | $ / shares								$ 16.67
Common Stock Voting Restrictions	10.00%
Common Stock Voting Restriction Less One Vote	10.00%
Common Stock Transfer Restrictions	5.00%
Common Stock Additional Transfer Restrictions					5.00%
Financial Guarantee Insurance Contracts, Accelerated Premium Revenue, Amount		$ 8,000,000	$ 1,000,000	$ 12,000,000
Number of Admitted Carriers Owned		5
Number of Admitted Carrier Owned		5
Number of Reportable Segments		3
LIBOR + 4.5% Senor Secured Notes Due 2026 | London Interbank Offered Rate (LIBOR) [Member]
Background And Basis Of Presentation [Line Items]
Debt Instrument, Interest Rate, Stated Percentage						4.50%
LSNI Secured Notes due 2023
Background And Basis Of Presentation [Line Items]
Repayment of Long-term Debt, Long-term Lease Obligation, and Capital Security		$ 1,163,000,000
Sitka Holdings, LLC | LIBOR + 4.5% Senor Secured Notes Due 2026
Background And Basis Of Presentation [Line Items]
Debt Instrument, Face Amount						$ 1,175,000,000