Background and Business Description - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions		12 Months Ended
	Apr. 29, 1991	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2015	Jul. 06, 2021	Feb. 12, 2018	May 01, 2013	Apr. 30, 2013
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
Common stock, shares authorized		130,000,000	130,000,000
Common Stock, Par or Stated Value Per Share									$ 0.01
Preferred stock, shares authorized		20,000,000	20,000,000
Preferred Stock, Par or Stated Value Per Share		$ 0.01							$ 0.01
Common stock, shares issued		46,477,068	45,865,081
Class of Warrant or Right, Exercise Price of Warrants or Rights								$ 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		$ 1	$ 12	$ 10
Business Acquisition, Percentage of Voting Interests Acquired		80.00%
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
Sitka Holdings, LLC | LIBOR + 4.5% Senor Secured Notes Due 2026
Background And Basis Of Presentation [Line Items]
Debt Instrument, Face Amount						$ 1,175