Fair Value Of Financial Instruments (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Contingent interest payment for debenture	$ (6,544)	$ (5,225)
Interest Payable	$ 6,800
Fair value assumptions expected volatility rate	27.00%
fair value assumptions credit spread	6.00%
Convertible Debt, Fair Value Disclosures	$ 3,200,000
Debt instrument fair value senior notes 2023	759,400
Debt instrument fair value senior notes 2025	$ 505,600
Minimum [Member]
fair value hypothetical increase decrease in volatility rate	22.00%
fair value hypothetical increase decrease in credit spread	5.00%
Maximum [Member]
fair value hypothetical increase decrease in volatility rate	32.00%
fair value hypothetical increase decrease in credit spread	7.00%