Components of Interest Expense attributable to the Convertible Notes (Detail) (USD $) In Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Debt Disclosure [Line Items]
Accretion of original issue discount	$ 583	$ 2,001	$ 2,788	$ 4,111
Amortization of debt issuance costs	895	964	1,962	2,109
4.5% Convertible Notes due 2012
Debt Disclosure [Line Items]
Contractual interest expense	421	2,587	3,009	5,175
Accretion of original issue discount	318	1,817	2,265	3,609
Amortization of debt issuance costs	55	310	389	641
Interest Expense, Debt, Total	$ 794	$ 4,714	$ 5,663	$ 9,425