Debt Extinguishment (Parenthetical) (Detail)	3 Months Ended	9 Months Ended
	Sep. 30, 2012 Notes Interest Rates Ranging From 1.625% to 7.95% Due From 2017 To 2018	Sep. 30, 2012 Notes Interest Rates Ranging From 1.625% to 7.95% Due From 2012 To 2018	Sep. 30, 2011 Notes Interest Rates Ranging From 6.2% to 9.375% Due From 2018 To 2025
Extinguishment of Debt [Line Items]
Interest rates range, minimum	1.625%	1.625%	6.20%
Interest rates range, maximum	6.95%	7.95%	9.375%
Original maturity date range, minimum	2017	2012	2018
Original maturity date range, maximum	2023	2023	2025