Financial Commitments (Summary Of Information Related To The Liability And Equity Components Of The Convertible Notes) (Details) - USD ($)	3 Months Ended	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Debt Instrument [Line Items]
Amortization of discount and debt issuance costs (non-cash interest expense)	$ 300,000		$ 600,000
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		(4,934,000)
Amortization of discount and debt issuance costs (non-cash interest expense)		340,000
Net carrying amount		148,606,000
Equity Component [Member] | Convertible Notes [Member]
Debt Instrument [Line Items]
Conversion feature		46,800,000
Allocated debt issuance costs		(1,507,000)
Net deferred tax liability		(18,787,000)
Net carrying amount		$ 26,506,000