Debt And Credit Arrangements Convertible Notes (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Debt Instrument [Line Items]
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 84.96
Interest accretion of convertible notes discount	$ 11,535,000	$ 10,662,000	$ 9,854,000
Amortization of Financing Costs	1,290,000	1,392,000	1,306,000
Convertible Notes, Due 2018 [Member] | Convertible Debt [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 250,000,000
Debt Instrument, Interest Rate, Stated Percentage	2.00%
Debt Instrument, Interest Rate, Effective Percentage	7.90%
Number Of Shares Of Convertible Debt Hedged And Capped Call	3,622
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 84.96
Proceeds from Issuance of Warrants	$ 48,848,000
Net Cost Of Convertible Note Hedge And All Capped Transactions	17,638,000
Convertible Debt, Noncurrent	215,634,000	204,099,000
Debt Instrument, Unamortized Discount	34,366,000	45,901,000
Interest Expense, Debt	16,535,000	15,662,000	14,854,000
Interest Expense, Debt, Excluding Amortization	5,000,000	5,000,000	5,000,000
Interest accretion of convertible notes discount	11,535,000	10,662,000	9,854,000
Debt Issuance Cost	7,277,000
Amortization of Financing Costs	$ 711,000	$ 711,000	$ 711,000
Debt Instrument, Convertible, Threshold Consecutive Trading Days	20 days
Debt Instrument, Convertible, Threshold Trading Days	30
Debt Instrument, Convertible, Threshold Percentage of Stock Price Trigger	130.00%
Debt Instrument, Convertible, Conversion Price	$ 69.03
Maximum days after any five trading day period in which trading price was less than 97 percent of last reported sale price	5 days
Convertible Notes Principal Amount Denominator For Trading Price	$ 1,000
Maximum Allowable Percentage Of The Product Of Last Reported Sale Price of Common Stock And Conversion Rate For Convertible Notes Payable	97.00%
Percent Of The Principal Amount Of The Convertible Notes Plus Accrued Interest To Be Purchased By The Company Subject Company Undergoing A Fundamental Change	100.00%
Debt Instrument, Fair Value Disclosure, Narrative	The fair value of the Convertible Notes was approximately 88% of their par value as of December 31, 2015 and approximately 95% of their par value as of December 31, 2014. The Convertible Notes are actively quoted instruments and, accordingly, the fair value of the Convertible Notes was determined using Level 1 inputs as defined in Note 11.
Liability Component [Member] | Convertible Notes, Due 2018 [Member] | Convertible Debt [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 170,885,000
Debt Issuance Cost	4,974,000
Equity Component [Member] | Convertible Notes, Due 2018 [Member] | Convertible Debt [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	79,115,000
Debt Issuance Cost	$ 2,303,000