Key Components of Convertible Debt (Detail) (Convertible Debt, USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Convertible Debt
Debt Instrument [Line Items]
Contractual interest expense on the coupon	$ 57,646,000	$ 60,375,000	$ 60,375,000
Amortization of the discount component recognized as interest expense	115,904,000	114,481,000	108,347,000
Total interest expense on the convertible debt	$ 173,550,000	$ 174,856,000	$ 168,722,000