Debt Schedule of Convertible Debt (Details) (USD $)	3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Jun. 30, 2014 3.75% Convertible Senior Subordinated Notes, due 2025 [Member]	Sep. 30, 2013 3.75% Convertible Senior Subordinated Notes, due 2025 [Member]	Sep. 30, 2014 3.75% Convertible Senior Subordinated Notes, due 2025 [Member]	Sep. 30, 2014 4.00% Junior Subordinated Convertible Debentures, due 2033 [Member]	Sep. 30, 2014 3.25% Convertible Senior Debentures, Due 2035 [Member]	Sep. 30, 2014 3.75% Convertible Senior Subordinated Notes Due 2042 [Member]	Sep. 30, 2014 3.5% Convertible senior subordinated debt [Domain]
Debt Instrument [Line Items]
Aggregate Principal of Convertible Debt, if Converted	$ 777,000,000		$ 777,000,000
Extinguishment of Debt, Amount						5,000,000
Debt Related Costs	72,000	50,868,000	7,832,000	50,868,000	8,000,000
Debt Instrument, Convertible, Carrying Amount of Equity Component							$ 6,913,000	$ 118,348,000	$ 245,433,000	$ 167,941,000	$ 208,200,000
Remaining amortization period for the debt discount (in years)							11 years 91 days	18 years 274 days	1 year 91 days	27 years 183 days	29 years 146 days
Debt Instrument, Interest Rate, Effective Percentage							8.25%	8.01%	7.63%	7.30%	7.70%