Derivative Instruments Not Designated as Hedging Instruments (Detail) (Not Designated as Hedging Instrument, USD $)			3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended				3 Months Ended		6 Months Ended
	Jun. 30, 2011 Cash Conversion Option Long-term debt	Dec. 31, 2010 Cash Conversion Option Long-term debt	Jun. 30, 2011 Cash Conversion Option Noncash convertible debt related expense	Jun. 30, 2010 Cash Conversion Option Noncash convertible debt related expense	Jun. 30, 2011 Cash Conversion Option Noncash convertible debt related expense	Jun. 30, 2010 Cash Conversion Option Noncash convertible debt related expense	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011 Note Hedge Other noncurrent assets	Dec. 31, 2010 Note Hedge Other noncurrent assets	Jun. 30, 2011 Note Hedge Noncash convertible debt related expense	Jun. 30, 2010 Note Hedge Noncash convertible debt related expense	Jun. 30, 2011 Note Hedge Noncash convertible debt related expense	Jun. 30, 2010 Note Hedge Noncash convertible debt related expense	Jun. 30, 2011 Contingent interest features of the Notes and Debentures Other noncurrent liabilities	Dec. 31, 2010 Contingent interest features of the Notes and Debentures Other noncurrent liabilities
Asset Derivatives:
Derivative											$ 88,542,000	$ 112,400,000
Liability Derivatives:
Derivative	90,724,000	115,994,000															0	0
Effect on income of derivative instruments			$ 14,758,000	$ 5,704,000	$ 25,270,000	$ 44,523,000	$ 138,000	$ (1,341,000)	$ 1,413,000	$ 582,000			$ (14,620,000)	$ (7,045,000)	$ (23,857,000)	$ (43,941,000)