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The Company and its Subsidiaries - Additional Information (Detail) (USD $)	12 Months Ended	3 Months Ended
	Dec. 31, 2014 Operations	Mar. 19, 2012	Dec. 31, 2013	Dec. 31, 2012	Sep. 25, 2008
Related Party Transaction [Line Items]
Assets sold of WMB in exchange for payment					$ 1,880,000,000
Debtors filed plan	Dec. 12, 2011
Plan Effective Date	Mar. 19, 2012
Claims distributed to parties-in-interest	6,500,000,000
Cash received from creditors	75,000,000us-gaap_ProceedsFromLoans
Senior credit facility	125,000,000
Senior credit facility for working capital	25,000,000
Senior credit facility for acquisitions and originations	100,000,000
Abandoned stock		8,370,000,000		8,370,000,000
Available and utilizable NOL	6,000,000,000us-gaap_OperatingLossCarryforwards
Number of operations	1wmih_NumberOfOperationsOperatedInRunoff
Common stock, shares authorized	500,000,000us-gaap_CommonStockSharesAuthorized		500,000,000us-gaap_CommonStockSharesAuthorized
Preferred stock, shares authorized	5,000,000us-gaap_PreferredStockSharesAuthorized		5,000,000us-gaap_PreferredStockSharesAuthorized
Common stock, par value	$ 0.00001		$ 0.00001
Preferred stock, par value	$ 0.00001		$ 0.00001
Common stock shares issued to new shareholders	194,670,501
Disputed equity escrow shares	5,329,499wmih_DisputedEquityEscrowShares
Shares remained in disputed equity escrow	2,921,555
Common stock, shares issued	202,343,245us-gaap_CommonStockSharesIssued		201,842,351us-gaap_CommonStockSharesIssued
Issuance of preferred stock, net of offering costs, Shares	1,000,000us-gaap_PreferredStockSharesIssued		0us-gaap_PreferredStockSharesIssued
Common stock, shares outstanding	202,343,245us-gaap_CommonStockSharesOutstanding		201,842,351us-gaap_CommonStockSharesOutstanding	201,156,078us-gaap_CommonStockSharesOutstanding
Preferred stock, shares outstanding	1,000,000us-gaap_PreferredStockSharesOutstanding		0us-gaap_PreferredStockSharesOutstanding	0us-gaap_PreferredStockSharesOutstanding
WMMRC [Member]
Related Party Transaction [Line Items]
Number of primary mortgage insurers	7
2012 Restricted Stock Unit Plan [Member]
Related Party Transaction [Line Items]
Common stock shares issued on effective date	200,000,000
Common Stock [Member]
Related Party Transaction [Line Items]
Issuance of common stock, Shares		200,000,000
Common Stock [Member] \| New WMI Shareholders [Member]
Related Party Transaction [Line Items]
Issuance of common stock, Shares		194,670,501
Common Stock [Member] \| Escrow Deposit [Member]
Related Party Transaction [Line Items]
Issuance of common stock, Shares		5,329,499
13% Senior First Lien Notes [Member]
Related Party Transaction [Line Items]
Issued aggregate principal amount	110,000,000
Debt instrument, interest rate, stated percentage	13.00%
13% Senior Second Lien Notes [Member]
Related Party Transaction [Line Items]
Issued aggregate principal amount	$ 20,000,000
Debt instrument, interest rate, stated percentage	13.00%