Financial Commitments (Summary Of Information Related To The Liability And Equity Components Of The Convertible Notes) (Details) - USD ($)	3 Months Ended	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Debt Instrument [Line Items]
Amortization of discount and debt issuance costs (non-cash interest expense)	$ 300,000		$ 800,000
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		(5,063,000)
Amortization of discount and debt issuance costs (non-cash interest expense)		2,405,000
Net carrying amount		150,542,000
Equity Component [Member] | Convertible Notes [Member]
Debt Instrument [Line Items]
Conversion feature		46,800,000
Allocated debt issuance costs		(1,547,000)
Net deferred tax liability		(18,815,000)
Net carrying amount		$ 26,438,000