Restriction on Distribution of Net Assets from Subsidiary - Additional Information (Detail) - USD ($)	Sep. 30, 2017	Sep. 13, 2017	Dec. 31, 2016
WMMRC [Member]
Financial Receivables Impaired Or Restructured [Line Items]
Total net assets	$ 17,700,000		$ 33,800,000
Maximum [Member] | Distribution from WMMRC to WMIH Deposited in Collateral Account [Member]
Financial Receivables Impaired Or Restructured [Line Items]
Approved amount for distribution		$ 10,700,000