Service Agreements and Related Party Transactions - Additional Information (Detail) $ / shares in Units, $ in Thousands			1 Months Ended	3 Months Ended	9 Months Ended
	Feb. 02, 2015 USD ($)	Oct. 14, 2014 Directors	Jun. 30, 2015 USD ($)	Sep. 30, 2015 USD ($)	Sep. 30, 2015 USD ($) $ / shares shares	Sep. 30, 2014 USD ($)	Jan. 05, 2015 USD ($)
Related Party Transaction [Line Items]
Payment of stock offering fee					$ 19,310	$ 3,348
WMMRC [Member]
Related Party Transaction [Line Items]
Administrative services agreement fee				$ 110	$ 110
Pro Rata Share of the Common Stock Allotment | shares					10,000,000
Percentage of Pro Rata Share of the Common Stock Election					5.00%
Lawsuit against number of former directors | Directors		16
Litigation settlement amount					$ 37,000
Proceeds from litigation settlement amount	$ 9,000
Litigation settlement reserve for reimbursement of contingent fees and expenses				3,000	$ 3,000		$ 3,000
WMMRC [Member] | Runoff Notes [Member]
Related Party Transaction [Line Items]
Principal amount of Runoff Notes | $ / shares					$ 1.00
WMMRC [Member] | Investment Management Agreement And Administrative Services Agreement [Member]
Related Party Transaction [Line Items]
Expenses incurred under the agreements					$ 1,100	$ 1,200
WMMRC [Member] | Investment Management Agreement [Member]
Related Party Transaction [Line Items]
Description of fee					fee equal to the product of (x) the ending dollar amount of assets under management during the calendar month in question and (y) .002 divided by 12.
WMI Holdings Corp [Member]
Related Party Transaction [Line Items]
Litigation settlement amount					$ 123
Proceeds from litigation settlement amount			$ 8,300
Litigation settlement reserve for reimbursement of contingent fees and expenses				500	500
Net proceeds from litigation settlement					34,000
Accrued legal expense				600	600
Other expenses				$ 477
Other income					7,800
KKR Capital Markets LLC [Member] | Redeemable Convertible Preferred Stock [Member]
Related Party Transaction [Line Items]
Payment of stock offering fee					8,250
Payment of additional deferred Fee					$ 8,250