The Company and its Subsidiaries - Additional Information (Detail) (USD $)	9 Months Ended	12 Months Ended						12 Months Ended	9 Months Ended		12 Months Ended		1 Months Ended	9 Months Ended	1 Months Ended
	Sep. 30, 2013 Operations	Dec. 31, 2012	Mar. 19, 2012	Sep. 25, 2008	Sep. 30, 2013 New WMI Shareholders [Member]	Sep. 30, 2013 Escrow Deposit [Member]	Sep. 30, 2013 WMI Holdings Corp. [Member]	Dec. 31, 2012 First Lien Note [Member]	Sep. 30, 2013 13% Senior First Lien Notes [Member]	Sep. 30, 2012 13% Senior First Lien Notes [Member]	Dec. 31, 2012 13% Senior First Lien Notes [Member]	Sep. 30, 2013 13% Senior Second Lien Notes [Member]	Jul. 17, 2012 WMMRC [Member]	Sep. 30, 2013 WMMRC [Member] Insurers	Jul. 17, 2012 Pmi [Member]
Related Party Transaction [Line Items]
Number of operations	1
Assets sold of WMB in exchange for payment				$ 1,880,000,000
Debtors field plan	Dec. 12, 2011
Plan Effective Date	Mar. 19, 2012
Claims distributed to parties-in-interest	6,500,000,000
Cash received from creditors	75,000,000
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
Issued aggregate principal amount									110,000,000			20,000,000
Debt amount percentage									13.00%			13.00%
Common stock, shares issued	201,842,351	201,156,078			194,670,501	5,329,499	200,000,000
Abandoned stock		8,370,000,000	8,370,000,000
Available and utilizable NOL		5,970,000,000
Number of primary mortgage insurers														7
Loss from contract termination		6,200,000
Amount paid by PMI													30,700,000		49,000,000
Cash paid to stockholders								25,000,000
Interest paid on Notes								3,700,000	9,700,000	3,700,000	3,700,000
Principal payment on Notes								$ 21,300,000