Capital Stock - Additional Information (Detail) (USD $)	12 Months Ended			9 Months Ended	0 Months Ended	1 Months Ended	0 Months Ended	3 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2012	Jan. 30, 2014	Jan. 30, 2014	Jan. 05, 2015	Mar. 19, 2012
Capital Stock Distribution [Line Items]
Common stock, shares authorized	500,000,000	500,000,000
Preferred stock, shares authorized	5,000,000	5,000,000
Common stock, par value	$ 0.00001	$ 0.00001
Preferred stock, par value	$ 0.00001	$ 0.00001
Convertible preferred stock, shares issued	1,000,000	0
Purchase price of convertible preferred stock maximum limit
Warrants to purchase in aggregate, shares					61,400,000	61,400,000
Preferred stock liquidation preference per share	$ 10.00
Convertible preferred stock conversion price	$ 1.10
Convertible Preferred Stock, shares	1,000,000
Warrants expiration period	5 years
Maximum percent of the voting shares of the emerging entity immediately prior to the confirmation of reorganization	50.00%				42.50%	42.50%		50.00%
Registration right period	180 days
Amount of restricted share grants	1,300,000	700,000	600,000
Award vesting period	3 years
Unamortized value of unvested restricted share grant	1,232,000	700,000	400,000	400,000
Equity-based compensation	807,000	401,000	143,000
Per share of unvested shares of common stock	$ 0.0001
Common stock, shares outstanding	202,343,245	201,842,351	201,156,078	201,156,078
Preferred stock, shares outstanding	1,000,000	0	0	0
Warrants to purchase common stock, outstanding	61,400,000	0	0	0
Restricted shares subject to repurchase [Member]
Capital Stock Distribution [Line Items]
Unvested shares	1,343,764	1,456,987	1,156,078	1,156,078
Successor [Member]
Capital Stock Distribution [Line Items]
Common stock, par value								0.00001
Preferred deemed dividend	(9,455,000)
Equity-based compensation	807,000	401,000		143,000
Series A Convertible Preferred Stock [Member]
Capital Stock Distribution [Line Items]
Convertible preferred stock, shares issued					1,000,000	1,000,000
Purchase price of convertible preferred stock maximum limit					11,100,000	11,100,000
Preferred stock liquidation preference	The Convertible Preferred Stock has rights substantially similar to those associated with WMIHC’s common stock, with the exception of a liquidation preference, conversion rights and customary anti-dilution protections. The Convertible Preferred Stock has a liquidation preference equal to the greater of (i) $10.00 per one million shares of Convertible Preferred Stock plus declared but unpaid dividends on such shares and (ii) the amount that the holder would be entitled to in a relevant transaction had the Convertible Preferred Stock been converted to common stock of WMIHC.
Convertible Preferred Stock [Member]
Capital Stock Distribution [Line Items]
Expiration of right to participating into future offering					Jan. 30, 2017
Preferred stock participation right	Additionally, until January 30, 2017, the Holders will have the right to purchase up to 50% of any future equity rights offerings or other equity issuance by WMIHC on the same terms as the equity issued to other investors in such transactions, in an aggregate amount of such offerings and issuances by WMIHC of up to $1.0 billion					Additionally, until January 30, 2017, the Holders will have the right to purchase up to 50% of any future equity rights offerings or other equity issuance by WMIHC on the same terms as the equity issued to other investors in such transactions, in an aggregate amount of such offerings and issuances by WMIHC of up to $1.0 billion
Convertible Preferred Stock [Member] | Maximum [Member]
Capital Stock Distribution [Line Items]
Maximum percent of the voting shares of the emerging entity immediately prior to the confirmation of reorganization					50.00%	50.00%
Percentage of rights vest with preferred shareholders to future offering					50.00%
Preferred stock participation value					1,000,000,000	1,000,000,000
Series B Preferred Stock [Member] | Subsequent Event
Capital Stock Distribution [Line Items]
Preferred stock, par value							$ 0.00001
Issuance of common stock, Shares							600,000
Convertible preferred stock, shares issued							600,000
Preferred stock liquidation preference per share							$ 1,000
Convertible preferred stock dividend rate							3.00%
Common Stock [Member]
Capital Stock Distribution [Line Items]
Issuance of common stock, Shares								200,000,000
Common Stock [Member] | Successor [Member]
Capital Stock Distribution [Line Items]
Common stock, shares outstanding	202,343,245	201,842,351	201,156,078	201,156,078				200,000,000
Warrant One [Member]
Capital Stock Distribution [Line Items]
Warrants to purchase common stock					30,700,000	30,700,000
Warrants to purchase common stock, exercise price					1.32	1.32
Warrant Two [Member]
Capital Stock Distribution [Line Items]
Warrants to purchase common stock					30,700,000	30,700,000
Warrants to purchase common stock, exercise price					1.43	1.43