Capital Stock - Additional Information (Detail) - USD ($)						1 Months Ended	3 Months Ended			9 Months Ended		12 Months Ended
	Jun. 01, 2016	May 15, 2015	Apr. 28, 2015	Jan. 05, 2015	Mar. 19, 2012	Jan. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Mar. 31, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015		May 11, 2015	May 10, 2015	Dec. 31, 2014	Jan. 30, 2014
Capital Stock Distribution [Line Items]
Common stock, shares authorized							3,500,000,000			3,500,000,000		3,500,000,000		3,500,000,000	500,000,000
Preferred stock, shares authorized							10,000,000			10,000,000				10,000,000	5,000,000
Common stock, par value							$ 0.00001			$ 0.00001		$ 0.00001		$ 0.00001	$ 0.00001
Preferred stock, par value							$ 0.00001			$ 0.00001				$ 0.00001	$ 0.00001
Conversion of shares														1
Warrants to purchase in aggregate, shares																	61,400,000
Warrants expiration period										5 years
Maximum percent of the voting shares of the emerging entity immediately prior to the confirmation of reorganization						42.50%	50.00%			50.00%
Registration right period										180 days
Preferred stock, shares issued							600,000			600,000		600,000
Escrow deposit				$ 598,500,000			$ 572,500,000			$ 572,500,000		$ 571,400,000
Preferred stock, shares outstanding							600,000			600,000		600,000
Derivative liability - embedded conversion feature							$ 58,261,000			$ 58,261,000		$ 120,848,000	[1]
Changes in fair value							(16,243,000)	$ 9,281,000		$ 62,587,000	$ (65,917,000)
Award vesting period										3 years
Unamortized value of unvested restricted share grant							$ 9,136,000			$ 9,136,000		10,000,000
Equity-based compensation										$ 484,000	961,000
Per share of unvested shares of common stock										$ 0.0001
Vested number of shares									190,070
Vested number of shares, outstanding									113,146
Vested number of shares, issued			76,924
Expected increase in additional paid in capital due to early vesting of equity shares												382,000
Expected increase in share based compensation due to early vesting of equity shares												$ 382,000
Common stock, shares issued							206,380,800			206,380,800		206,168,035
Common stock, shares outstanding							206,380,800			206,380,800		206,168,035
Warrants to purchase common stock, Issued							61,400,000			61,400,000		61,400,000
Warrants to purchase common stock, outstanding							61,400,000			61,400,000		61,400,000
EXEC Grants [Member]
Capital Stock Distribution [Line Items]
Share price		$ 2.76
Restricted stock fair value										$ 8,300,000
Restricted stock price per share										$ 2.34
Restricted stock award [Member]
Capital Stock Distribution [Line Items]
Amount of restricted stock grants	$ 500,000		$ 700,000
Share price	$ 2.35	$ 2.76	$ 2.60
Unvested shares							6,380,800			6,380,800		6,168,035				2,343,245
Number of Restricted Stock Awards Outstanding, Restricted stock awards granted	212,765	3,555,556	269,234							212,765		3,824,790
Restricted stock award [Member] | Chief Executive Officer [Member]
Capital Stock Distribution [Line Items]
Number of Restricted Stock Awards Outstanding, Restricted stock awards granted		1,777,778
Restricted stock award [Member] | Chief Operating Officer [Member]
Capital Stock Distribution [Line Items]
Number of Restricted Stock Awards Outstanding, Restricted stock awards granted		1,777,778
Restricted stock award [Member] | EXEC Grants [Member]
Capital Stock Distribution [Line Items]
Amount of restricted stock grants		$ 9,800,000
Restricted shares subject to repurchase [Member]
Capital Stock Distribution [Line Items]
Unvested shares							4,039,591			4,039,591		4,197,396				1,343,764
Number of Restricted Stock Awards Outstanding, Restricted stock awards granted										212,765		3,824,790
Minimum [Member]
Capital Stock Distribution [Line Items]
Preferred stock liquidation preference per share							$ 10.00			$ 10.00
Convertible Series A Preferred Stock [Member]
Capital Stock Distribution [Line Items]
Preferred stock, par value							$ 0.00001			$ 0.00001		$ 0.00001
Preferred stock, shares issued							1,000,000			1,000,000		1,000,000					1,000,000
Purchase price of convertible preferred stock maximum limit													[1]				$ 11,100,000
Preferred stock liquidation preference										The Series A Preferred Stock has rights substantially similar to those associated with WMIH’s common stock, with the exception of a liquidation preference, conversion rights and customary anti-dilution protections. The Series A Preferred Stock has a liquidation preference equal to the greater of (i) $10.00 per one million shares of Series A 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 Series A Preferred Stock been converted to common stock of WMIH.
Convertible preferred stock conversion price										$ 1.10
Preferred deemed dividend										$ 9,500,000
Preferred stock, shares outstanding							1,000,000			1,000,000		1,000,000
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 Series A Holders will have the right to purchase up to 50% of any future equity rights offerings or other equity issuance by WMIH on the same terms as the equity issued to other investors in such transactions, in an aggregate amount of such offerings and issuances by WMIH of up to $1.0 billion
Convertible Preferred Stock [Member] | Maximum [Member]
Capital Stock Distribution [Line Items]
Maximum percent of the voting common shares of the emerging entity immediately prior to the confirmation of reorganization						50.00%
Percentage of rights vest with preferred shareholders to future offering						50.00%
Preferred stock participation value						$ 1,000,000,000
Redeemable Convertible Series B Preferred Stock [Member]
Capital Stock Distribution [Line Items]
Issuance of common stock, Shares												600,000
Preferred stock, shares issued				600,000			600,000			600,000		600,000
Preferred stock dividend rate calculated on interest rate				3.00%
Preferred stock, redemption date										Jan. 05, 2018
Preferred stock, shares outstanding							600,000			600,000		600,000
Preferred stock, redemption amount							$ 600,000,000			$ 600,000,000
Number of trading periods										20 days
Conversion ceiling price of common stock							$ 2.25			$ 2.25
Conversion floor price of common stock							$ 1.75			$ 1.75
Derivative liability - embedded conversion feature				$ 66,200,000			$ 58,300,000	132,100,000		$ 58,300,000	132,100,000	$ 120,800,000
Changes in fair value							$ 16,200,000	$ (9,300,000)		$ (62,500,000)	$ 65,900,000	$ 54,600,000
Share price		$ 2.25
Redeemable Convertible Series B Preferred Stock [Member] | Maximum [Member]
Capital Stock Distribution [Line Items]
Conversion ceiling price of common stock							$ 2.25			$ 2.25
Common Stock [Member]
Capital Stock Distribution [Line Items]
Issuance of common stock, Shares					200,000,000
Warrant One [Member]
Capital Stock Distribution [Line Items]
Warrants to purchase common stock																	30,700,000
Warrants to purchase common stock, exercise price																	$ 1.32
Warrant Two [Member]
Capital Stock Distribution [Line Items]
Warrants to purchase common stock																	30,700,000
Warrants to purchase common stock, exercise price																	$ 1.43

[1] Balances derived from audited financial statements as of December 31, 2015.