Key Components of Convertible Debt (Detail) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Debt Instrument [Line Items]
Contractual interest expense on the coupon	$ 15,078,000	$ 15,094,000	$ 45,266,000	$ 45,282,000
Amortization of the discount component recognized as interest expense	31,045,000	29,041,000	90,367,000	85,128,000
Total interest expense on the convertible debt	$ 46,123,000	$ 44,135,000	$ 135,633,000	$ 130,410,000