Assets and Liabilities at Fair Value (Parenthetical) (Detail) (USD $)	6 Months Ended						1 Months Ended	3 Months Ended
	Mar. 19, 2012	Sep. 30, 2012	Mar. 19, 2012 Reorganization Adjustments [Member]		Sep. 30, 2012 Successor [Member]	Mar. 19, 2012 Successor [Member]	Mar. 19, 2012 Predecessor [Member]	Mar. 19, 2012 Predecessor [Member]	Dec. 31, 2011 Predecessor [Member]	Mar. 19, 2012 Fair Value Adjustments [Member]		Mar. 19, 2012 WMMRC [Member]	Mar. 19, 2012 Runoff Notes [Member]
Fresh-Start Adjustment [Line Items]
Common stock, par value		$ 0.00001	$ 0.00001	[1]	$ 0.00001	$ 0.00001	$ 1	$ 1	$ 1.00000	$ 1	[2]
Common stock, shares authorized		500,000,000	500,000,000	[1]	500,000,000	500,000,000
Common stock, shares outstanding		200,000,000	200,000,000	[1]	200,000,000	200,000,000	1,000	1,000	1,000	1,000	[2]
Common stock, shares issued		200,000,000	200,000,000	[1]	200,000,000	200,000,000	1,000	1,000	1,000	1,000	[2]
Common stock, shares issued		200,000,000	200,000,000	[1]	200,000,000	200,000,000	1,000	1,000	1,000	1,000	[2]
Cash contributed to the Company by creditors	$ 75,000,000							$ 75,000,000
Court's valuation of WMMRC												140,000,000
Outstanding amount of notes													130,000,000
Common stock, par value		$ 0.00001	$ 0.00001	[1]	$ 0.00001	$ 0.00001	$ 1	$ 1	$ 1.00000	$ 1	[2]
Common stock, shares outstanding		200,000,000	200,000,000	[1]	200,000,000	200,000,000	1,000	1,000	1,000	1,000	[2]
Common stock, shares issued		200,000,000	200,000,000	[1]	200,000,000	200,000,000	1,000	1,000	1,000	1,000	[2]
Net Assets or Equity Value												171,600,000
Loss contract fair market value reserve	63,100,000	63,100,000			52,368,000	63,100,000
Increase in equity value							194,700,000
Reduction in WMMRC's FMV	8,400,000											8,400,000
Value related to NOLs	$ 70,000,000
Valuation allowance	100.00%

[1] These adjustments are necessary to give effect to the Plan, including the receipt of cash proceeds associated with the contribution of cash from certain creditors, issuance of debt securities, issuance of 200 million shares of common stock and other transactions as contemplated under the Plan.

[2] These adjustments are necessary to reflect assets and liabilities at fair value and elimination of Predecessor equity. The primary operating business of the Successor is the WMMRC subsidiary which has a net asset value higher than its Fair Market Value ("FMV").