Fair Value Of Financial Instruments (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
contingent interest payment for debenture	$ 0	$ 0	$ (5,225)	$ 0
Interest Payable	5,500		$ 5,500
Fair value assumptions expected volatility rate			28.00%
fair value hypothetical increase decrease in volatility rate			5.00%
fair value assumptions credit spread			4.00%
fair value hypothetical increase decrease in credit spread			1.00%
Convertible Debt, Fair Value Disclosures	2,300,000		$ 2,300,000
Debt instrument fair value senior notes 2023	721,900		721,900
Debt instrument fair value senior notes 2025	$ 498,800		$ 498,800