Fair Value Measurements Fair Value Measurements (Details 1) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013 Convertible Senior Notes Due March 2028 [Member]	Dec. 31, 2012 Convertible Senior Notes Due March 2028 [Member]	Jan. 29, 2013 7.875% Senior Notes due 2021 [Member]	Mar. 31, 2013 Portion at Other than Fair Value, Fair Value Disclosure [Member]	Dec. 31, 2012 Portion at Other than Fair Value, Fair Value Disclosure [Member]	Mar. 31, 2013 Portion at Other than Fair Value, Fair Value Disclosure [Member] Fair Value, Inputs, Level 1 [Member]	Dec. 31, 2012 Portion at Other than Fair Value, Fair Value Disclosure [Member] Fair Value, Inputs, Level 1 [Member]	Mar. 31, 2013 Portion at Other than Fair Value, Fair Value Disclosure [Member] Fair Value, Inputs, Level 2 [Member]	Dec. 31, 2012 Portion at Other than Fair Value, Fair Value Disclosure [Member] Fair Value, Inputs, Level 2 [Member]	Mar. 31, 2013 Portion at Other than Fair Value, Fair Value Disclosure [Member] Fair Value, Inputs, Level 3 [Member]	Dec. 31, 2012 Portion at Other than Fair Value, Fair Value Disclosure [Member] Fair Value, Inputs, Level 3 [Member]	Mar. 31, 2013 Portion at Other than Fair Value, Fair Value Disclosure [Member] Convertible Senior Notes Due March 2028 [Member]	Dec. 31, 2012 Portion at Other than Fair Value, Fair Value Disclosure [Member] Convertible Senior Notes Due March 2028 [Member]	Mar. 31, 2013 Portion at Other than Fair Value, Fair Value Disclosure [Member] Convertible Senior Notes Due March 2028 [Member] Fair Value, Inputs, Level 1 [Member]	Dec. 31, 2012 Portion at Other than Fair Value, Fair Value Disclosure [Member] Convertible Senior Notes Due March 2028 [Member] Fair Value, Inputs, Level 1 [Member]	Mar. 31, 2013 Portion at Other than Fair Value, Fair Value Disclosure [Member] Convertible Senior Notes Due March 2028 [Member] Fair Value, Inputs, Level 2 [Member]	Dec. 31, 2012 Portion at Other than Fair Value, Fair Value Disclosure [Member] Convertible Senior Notes Due March 2028 [Member] Fair Value, Inputs, Level 2 [Member]	Mar. 31, 2013 Portion at Other than Fair Value, Fair Value Disclosure [Member] Convertible Senior Notes Due March 2028 [Member] Fair Value, Inputs, Level 3 [Member]	Dec. 31, 2012 Portion at Other than Fair Value, Fair Value Disclosure [Member] Convertible Senior Notes Due March 2028 [Member] Fair Value, Inputs, Level 3 [Member]	Mar. 31, 2013 Portion at Other than Fair Value, Fair Value Disclosure [Member] 7.875% Senior Notes due 2021 [Member]	Mar. 31, 2013 Portion at Other than Fair Value, Fair Value Disclosure [Member] 7.875% Senior Notes due 2021 [Member] Fair Value, Inputs, Level 1 [Member]	Mar. 31, 2013 Portion at Other than Fair Value, Fair Value Disclosure [Member] 7.875% Senior Notes due 2021 [Member] Fair Value, Inputs, Level 2 [Member]	Mar. 31, 2013 Portion at Other than Fair Value, Fair Value Disclosure [Member] 7.875% Senior Notes due 2021 [Member] Fair Value, Inputs, Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Fair Value												$ 5,394	$ 48,220	$ 5,394	$ 48,220	$ 0	$ 0	$ 0	$ 0	$ 300,000	$ 0	$ 300,000	$ 0
Royalty Obligation Fair value				$ 85,290	$ 90,617	$ 0	$ 0	$ 85,290	$ 90,617	$ 0	$ 0
Debt Instrument, Interest Rate, Stated Percentage	3.25%	3.25%	7.875%