Capital Stock - Additional Information (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	1 Months Ended	12 Months Ended			1 Months Ended	12 Months Ended
	Oct. 18, 2012	Dec. 31, 2012 Y	Dec. 31, 2011	Dec. 31, 2010	Mar. 19, 2013 Subsequent Events [Member]	Dec. 31, 2012 Subsequent Events [Member]	Dec. 31, 2012 WMI Holdings Corp [Member]
Capital Stock Distribution [Line Items]
Common stock, shares authorized		500,000,000
Preferred stock, shares authorized		5,000,000
Preferred stock, par value		$ 0.00001
Common stock, par value		$ 0.00001
Common stock, shares issued		201,156,078					200,000,000
Restricted common stock issued	1,156,078	1,156,078
Amount of restricted share grants		$ 550
Intrinsic value of restricted share grants		$ 0	$ 0	$ 0
Award vesting period		3 years				3 years
Unamortized value of unvested restricted share grant		407	0	0
Amortized period for unvested restricted share		2.2
Stock-based compensation		$ 143	$ 0	$ 0
Award vesting rights						1/3 per year
Number of shares vested					385,360
Per share of unvested shares of common stock		$ 0.0001
Common stock, shares outstanding		201,156,078
Preferred stock, shares issued		0
Preferred stock, shares outstanding		0