Debt Fair Value of Financial Instruments (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Long-term Debt, Gross	$ 2,475,228	$ 2,381,929
Debt Instrument, Unamortized Discount	468,229	422,681
7.75% Senior Subordinated Notes, Due 2020 [Member]
Long-term Debt, Gross	550,000	550,000
Long-term Debt, Fair Value	599,500	591,300
3.75% Convertible Senior Subordinated Notes, due 2025 [Member]
Long-term Debt, Gross	318,054	575,000
Long-term Debt, Fair Value	438,900	816,500
Long-term Debt	203,394	361,345
Debt Instrument, Unamortized Discount	114,660	213,655
4.00% Junior Subordinated Convertible Debentures, due 2033 [Member]
Long-term Debt, Gross	345,000	345,000
Long-term Debt, Fair Value	322,600	318,800
Long-term Debt	205,599	203,675
Debt Instrument, Unamortized Discount	139,401	141,325
3.25% Convertible Senior Debentures, Due 2035 [Member]
Long-term Debt, Gross	427,500	452,500
Long-term Debt, Fair Value	426,400	404,600
Long-term Debt	374,123	384,799
Debt Instrument, Unamortized Discount	53,377	67,701
3.75% Convertible Senior Subordinated Notes Due 2042 [Member]
Long-term Debt, Gross	390,000	0
Long-term Debt, Fair Value	377,300	0
Long-term Debt	229,209	0
Debt Instrument, Unamortized Discount	$ 160,791	$ 0