Subsequent Events (Narrative) (Detail) (USD $) In Millions, unless otherwise specified	1 Months Ended						3 Months Ended		1 Months Ended		1 Months Ended
	Apr. 30, 2013 Subsequent Event [Member]	Mar. 31, 2013 Subsequent Event [Member]	Apr. 30, 2013 Subsequent Event [Member] Five And One Over Two Senior Notes [Member]	Mar. 31, 2013 Subsequent Event [Member] Five And One Over Two Senior Notes [Member]	Oct. 31, 2012 Subsequent Event [Member] Five And One Over Two Senior Notes [Member]	Apr. 30, 2013 Subsequent Event [Member] 9 5/8% Notes [Member]	Mar. 31, 2013 9 5/8% Notes [Member]	Mar. 31, 2013 9 3/4% Notes [Member]	Apr. 30, 2013 9 3/4% Notes [Member] Subsequent Event [Member]	Mar. 31, 2013 9 3/4% Notes [Member] Subsequent Event [Member]	Apr. 30, 2013 9 5/8% Notes [Member] Subsequent Event [Member]	Mar. 31, 2013 Long Term Borrowings [Member] 9 5/8% Notes [Member]	Mar. 31, 2013 Long Term Borrowings [Member] 9 3/4% Notes [Member]
Subsequent Event [Line Items]
Maturity Dates	April 2023						March 2018	March 2020	March 2020		March 2018
Convertible senior notes interest percentage				5.50%		9.625%				9.75%		9.625%	9.75%
Debt Instrument Offering Value			$ 500		$ 500
Tender Offer To Purchase Senior Notes		450									450
Tender Offer Paid on Notes	$ 326								$ 26