Long-Term Debt (Convertible Senior Notes Dues 2032) (Details) - USD ($)	1 Months Ended
	Mar. 31, 2012	Jun. 30, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Long-term debt, carrying value		$ 812,004,000
Unamortized debt discount		17,992,000	$ 20,900,000
Convertible Senior Notes 2032 [Member]
Debt Instrument [Line Items]
Long-term debt, carrying value	$ 200,000,000	200,000,000
Debt instrument interest rate	3.25%
Debt instrument, frequency of periodic payment	semi-annually
Debt instrument, maturity date	Mar. 15, 2032
Convertible Senior Notes, shares of common stock	39.9752
Base principal amount	$ 1,000
Per share conversion price	$ 25.02
Debt instrument, redemption price, percentage of principal amount redeemed	100.00%
Unamortized debt discount	$ 35,400,000	$ 17,992,000
Expected life used to estimate fair value	6 years
Effective interest rate		6.90%
Debt Instrument, Convertible, Carrying Amount of Equity Component		$ 22,500,000