Financial Commitments (Summary Of Information Related To The Liability And Equity Components Of The Convertible Notes) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Net deferred tax liability	$ (129,661,000)	$ (122,822,000)
Convertible Notes [Member]
Debt Instrument [Line Items]
Principal	200,000,000
Liability Component [Member] | Convertible Notes [Member]
Debt Instrument [Line Items]
Principal	200,000,000
Conversion feature	(46,800,000)
Allocated debt issuance costs	(5,051,000)
Amortization of discount and debt issuance costs (non-cash interest expense)	4,519,000
Net carrying amount	152,668,000
Equity Component [Member] | Convertible Notes [Member]
Debt Instrument [Line Items]
Conversion feature	46,800,000
Allocated debt issuance costs	(1,543,000)
Net deferred tax liability	(18,815,000)
Net carrying amount	$ 26,442,000