Financial Commitments (Reconciliation Of Outstanding Debt Balance To Reported Debt Balance) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Outstanding Long-Term Debt	$ 815,591
Unamortized Discount and Issuance Cost	(56,072)	$ (6,697)
Total debt	759,519	817,684
2014 Revolver [Member]
Debt Instrument [Line Items]
Outstanding Long-Term Debt	152,500	158,000
Unamortized Discount and Issuance Cost	(4,510)	(2,185)
Total debt	147,990	155,815
Term Loan [Member]
Debt Instrument [Line Items]
Outstanding Long-Term Debt	57,000	223,750
Unamortized Discount and Issuance Cost	(2,350)	(1,630)
Total debt	54,650	222,120
2010 Notes [Member]
Debt Instrument [Line Items]
Outstanding Long-Term Debt	300,000	300,000
Unamortized Discount and Issuance Cost	(1,880)	(2,882)
Total debt	298,120	$ 297,118
Convertible Notes [Member]
Debt Instrument [Line Items]
Outstanding Long-Term Debt	200,000
Unamortized Discount and Issuance Cost	(47,332)
Total debt	$ 152,668