Subsequent Events - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	1 Months Ended
Jul. 17, 2012
PMI [Member]
Subsequent Event [Line Items]
Amount paid by PMI	$ 49.0
WMMRC [Member]
Subsequent Event [Line Items]
Amount paid by PMI	$ 30.7

Amount Paid To Third Party Under Commutation Agreement

No definition available.

Name:	wmih_AmountPaidToThirdPartyUnderCommutationAgreement
Namespace Prefix:	wmih_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration