Service Agreements and Related Party Transactions - Additional Information (Detail) (WMMRC [Member], USD $)	0 Months Ended	12 Months Ended	0 Months Ended	9 Months Ended	12 Months Ended
	Oct. 14, 2014 Directors	Dec. 31, 2014	Jan. 05, 2015	Dec. 31, 2012	Dec. 31, 2013	Dec. 31, 2011
Related Party Transaction [Line Items]
Pro Rata Share of the Common Stock Allotment		10,000,000
Percentage of Pro Rata Share of the Common Stock Election		5.00%
Percentage of interest in Litigation Proceeds		50.00%
Principal amount of Runoff Notes		$ 1.00
Lawsuit against number of former directors	16
Litigation settlement amount		$ 37,000,000
Subsequent Event
Related Party Transaction [Line Items]
Proceeds from litigation settlement amount			9,000,000
Investment Management Agreement And Administrative Services Agreement [Member]
Related Party Transaction [Line Items]
Expenses incurred under the agreements		1,500,000		1,500,000	1,700,000	0
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.
Administrative Services Agreement [Member]
Related Party Transaction [Line Items]
Administrative services agreement fee		$ 110,000