Interim Financial Statements (Details 2) (USD $) In Thousands	Sep. 30, 2011	Dec. 31, 2010
Summary of fair value of subordinated notes
Net carrying amount of the liability component	$ 851,569	$ 779,878
7.75% senior subordinated notes due 2016 [Member]
Summary of fair value of subordinated notes
Net carrying amount of the liability component	375,000	375,000
Net fair amount of the liability component	375,000
3.5% senior subordinated convertible notes due 2026 [Member]
Summary of fair value of subordinated notes
Net carrying amount of the liability component	63,324	148,884
Net fair amount of the liability component	$ 59,366