Subsequent Events - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended				1 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2014 Revolving Credit Facility	Mar. 31, 2014 2014 Debt Refinancing 11.5% Senior Notes due 2018	Apr. 09, 2014 Subsequent Event Revolving Credit Facility	Apr. 09, 2014 Subsequent Event New Senior Secured Notes	Apr. 09, 2014 Subsequent Event New Senior Secured Notes Option One	Apr. 09, 2014 Subsequent Event New Senior Secured Notes Option Two	Apr. 09, 2014 Subsequent Event New Senior Secured Notes Option Three	Apr. 09, 2014 Subsequent Event New Senior Secured Notes Maximum Option One	Apr. 09, 2014 Subsequent Event New Senior Secured Notes Maximum Option Three	Apr. 09, 2014 Subsequent Event New Senior Secured Notes Minimum Option One	Apr. 09, 2014 Subsequent Event New Unsecured Notes	Apr. 09, 2014 Subsequent Event New Unsecured Notes Option One	Apr. 09, 2014 Subsequent Event New Unsecured Notes Option Two	Apr. 09, 2014 Subsequent Event New Unsecured Notes Maximum Option One	Apr. 09, 2014 Subsequent Event New Unsecured Notes Minimum Option One	Apr. 09, 2014 Subsequent Event 2014 Debt Refinancing New Senior Secured Notes	Apr. 09, 2014 Subsequent Event 2014 Debt Refinancing New Unsecured Notes	Apr. 09, 2014 Subsequent Event 2014 Debt Refinancing Refinancing Transaction	Apr. 09, 2014 Subsequent Event 2014 Debt Refinancing Refinancing Transaction 11.5% Senior Notes due 2018
Subsequent Event [Line Items]
Face or Principal amount of Debt Instrument						$ 765														$ 275	$ 660	$ 765
Maturity date																				2022	2022		2018
Interest rate								5.625%							6.75%					5.625%	6.75%		11.50%
Redemption payment																						869
Repayments of long term debt outstanding																							765
Tender/Call premium on redemption of debt																						85
Secured Notes consent fees																						19
Accrued interest paid	33	10	101	110																		3
Loss on extinguishment of debt				(83)																		(141)
Unamortized discount																						13
Unamortized debt issuance costs related to Old Secured Notes																						$ 24
Credit Facility maturity date					Nov. 01, 2017		Apr. 01, 2019
Payment of interest, terms								payable semi-annually in arrears on April 15 and October 15							payable semi-annually in arrears on April 15 and October 15
Payment of interest, commencing date								Oct. 15, 2014							Oct. 15, 2014
Redemption period, end date									Apr. 15, 2017	Apr. 15, 2017	Apr. 15, 2017						Apr. 15, 2017	Apr. 15, 2017
Percentage of original aggregate principal amount												40.00%	10.00%			40.00%
Redemption price percentage									105.625%	100.00%	103.00%					106.75%	100.00%
Percentage of aggregate principal amount remains outstanding														50.00%					50.00%
Redemption period									90 days		12 months
Percentage of principal amount purchased by cash								101.00%							101.00%