Fair Value Of Financial Instruments (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Contingent interest payment for debenture	$ (5,534)	$ 0	$ (10,759)	$ 0
Interest Payable	6,400		$ 6,400
Fair value assumptions expected volatility rate			25.00%
fair value assumptions credit spread			5.00%
Convertible Debt, Fair Value Disclosures	2,600,000		$ 2,600,000
Debt instrument fair value senior notes 2023	734,100		734,100
Debt instrument fair value senior notes 2025	$ 504,700		$ 504,700
Minimum [Member]
fair value hypothetical increase decrease in volatility rate			20.00%
fair value hypothetical increase decrease in credit spread			4.00%
Maximum [Member]
fair value hypothetical increase decrease in volatility rate			30.00%
fair value hypothetical increase decrease in credit spread			6.00%