Components of Interest Expense attributable to the Convertible Notes (Detail) (USD $) In Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Debt Disclosure [Line Items]
Accretion of original issue discount	$ 315	$ 1,986	$ 3,103	$ 6,097
Amortization of debt issuance costs	747	883	2,709	2,992
4.5% Convertible Notes due 2012
Debt Disclosure [Line Items]
Contractual interest expense	55	2,588	3,064	7,763
Accretion of original issue discount	43	1,868	2,308	5,477
Amortization of debt issuance costs	7	300	396	941
Interest Expense, Debt, Total	$ 105	$ 4,756	$ 5,768	$ 14,181