Debt And Credit Arrangements 2018 Notes (Details) $ / shares in Units, $ in Thousands		3 Months Ended	12 Months Ended
		Dec. 31, 2017 USD ($) $ / shares shares	Dec. 31, 2017 USD ($) $ / shares shares		Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Nov. 05, 2017 USD ($)
Debt Instrument [Line Items]
Debt Instrument, Face Amount		$ 250,000	$ 250,000
Debt Instrument, Interest Rate, Stated Percentage		2.00%	2.00%
Debt Instrument, Repurchase Amount		$ 192,900	$ 192,900
Long-term Debt, Maturities, Repayments of Principal in Next Twelve Months	[1]	60,900	60,900
Loss on extinguishment of debt		4,900	4,900		$ 0	$ 0
Interest Paid			9,300		5,600	5,100
Interest accretion of convertible notes discount			12,800		12,500	11,500
Amortization of Debt Issuance Costs			1,279		1,284	1,290
Convertible Notes, Due 2018 [Member]
Debt Instrument [Line Items]
Long-term Debt, Maturities, Repayments of Principal in Next Twelve Months		57,100	57,100
Convertible Notes, Due 2018 [Member] | Convertible Debt [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount		$ 57,100	$ 57,100		250,000
Debt Instrument, Interest Rate, Stated Percentage		2.00%	2.00%
Debt Instrument, Interest Rate, Effective Percentage		7.90%	7.90%
Repayments of Debt			$ 195,900
Debt Instrument, Repurchase Amount		$ 192,900	192,900
Interest on Convertible Debt, Net of Tax			1,000
Extinguishment of Debt, Amount			194,900
Long-term Debt, Maturities, Repayments of Principal in Next Twelve Months		57,100	57,100
Convertible Debt, Current		$ 55,100	$ 55,100
Fair Value Inputs, Discount Rate			4.80%
Convertible Debt					227,000		$ 184,700
Loss on extinguishment of debt			$ 4,700	[2]	0	0
Interest Paid			$ 1,000
Equivalent Shares Of Common Stock Per 1000 Principal Amount Of Convertible Notes | shares			14.4865
Debt Instrument, Convertible, Conversion Price | $ / shares		$ 69.03	$ 69.03
Debt Instrument, Convertible, Threshold Consecutive Trading Days			20
Debt Instrument, Convertible, Threshold Trading Days			30
Interest accretion of convertible notes discount			$ 11,800		12,500	11,500
Interest Expense, Debt, Excluding Amortization			4,300		5,000	5,000
Interest Expense, Debt			16,100		17,500	16,500
Gain (Loss) on Extinguishment of Debt, before Write off of Debt Issuance Cost			4,300		0	0
Write off of Deferred Debt Issuance Cost			400		0	0
Amortization of Debt Issuance Costs			$ 619		$ 711	$ 711
Class of Warrant or Right, Exercise Price of Warrants or Rights | $ / shares		$ 84.96	$ 84.96
Number of Shares Underlying Warrants | shares		800,000	800,000
Convertible Notes, Due 2018 [Member] | Convertible Debt [Member] | Liability Component [Member]
Debt Instrument [Line Items]
Extinguishment of Debt, Amount			$ 189,000
Convertible Notes, Due 2018 [Member] | Convertible Debt [Member] | Equity Component [Member]
Debt Instrument [Line Items]
Extinguishment of Debt, Amount			5,800
Liability Component [Member] | Convertible Notes, Due 2018 [Member] | Convertible Debt [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount		$ 170,900	170,900
Equity Component [Member] | Convertible Notes, Due 2018 [Member] | Convertible Debt [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount		$ 79,100	$ 79,100

[1] (1) Includes the $57.1 fully accreted amount of our 2018 Notes and $3.8 current maturities related to foreign facilities.

[2] (1) During the year ended December 31, 2017, we wrote off $0.2 of unamortized debt issuance costs related to our senior secured revolving credit facility. When combined with the total loss on extinguishment associated with the 2018 Notes, consolidated loss on extinguishment is $4.9.