Debt and Credit Arrangements Convertible Notes (Details) (USD $) Share data in Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
Debt Instrument [Line Items]
Class of Warrant or Right, Exercise Price of Warrants or Rights	84.96		84.96
Interest accretion of convertible notes discount			$ 7,317,000	$ 6,764,000
Financing costs amortization	326,000	326,000	979,000	1,203,000
Minimum Trading Days Required During Thirty Consecutive Trading Days Where Last Reported Sales Price Is At Least 130 Percent Of Conversion Price	20 days		20 days
Maximum Days After Any Five Trading Day Period In Which Trading Price Was Less Than 97 Percent Of Last Reported Sale Price of Common Stock Times Conversion Rate	5 days		5 days
Share Price	$ 123.04		$ 123.04
Debt Instrument, Convertible, If-converted Value in Excess of Principal	195,603,000
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%		100.00%
Current convertible notes	190,900,000		190,900,000		0
Convertible notes conversion feature	59,100,000		59,100,000		0
Assets And Liabilities For Which Fair Value Only Is Disclosed, Fair Value Of Convertible Notes As A Percentage Of Par Value	188.00%		188.00%		124.00%
Convertible Notes Payable [Member] | Convertible Notes, Due 2018 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	250,000,000		250,000,000
Debt Instrument, Interest Rate, Stated Percentage	2.00%		2.00%
Debt Instrument, Convertible, Effective Interest Rate	7.90%		7.90%
Number Of Shares Of Convertible Debt Hedged And Capped Call	3,622		3,622
Class of Warrant or Right, Exercise Price of Warrants or Rights	84.96		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	170,885,000		170,885,000
Carrying amount of equity component	79,115,000		79,115,000
Percentage Used As Debt Rate For Present Value Of Cash Flows	7.90%		7.90%
Unamortized discount	59,100,000	66,417,000	59,100,000	66,417,000
Debt Instrument, Convertible, Interest Expense	3,737,000	3,549,000	11,067,000	10,514,000
Interest Expense, Debt, Excluding Amortization	1,250,000	1,250,000	3,750,000	3,750,000
Interest accretion of convertible notes discount	2,487,000	2,299,000	7,317,000	6,764,000
Deferred Finance Costs, Gross	7,277,000		7,277,000
Financing costs amortization	178,000	178,000	533,000	533,000
Minimum Percentage Of Conversion Price Of Convertible Notes On 20 Of 30 Trading Days For The Options To Be Convertible	130.00%		130.00%
Debt Instrument, Convertible, Conversion Price	$ 69.03		$ 69.03
Convertible Notes Principal Amount Denominator For Trading Price	1,000		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%		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%		100.00%
Debt Instrument, Convertible, 130% of Conversion Price	$ 89.74		$ 89.74
Current convertible notes	190,900,000		190,900,000
Convertible notes conversion feature	59,100,000		59,100,000
Senior Term Loan Due 2017 [Member] | Senior Credit Facility [Member]
Debt Instrument [Line Items]
Financing costs amortization	148,000	148,000	446,000	670,000
Additional Paid-in Capital [Member] | Convertible Notes Payable [Member] | Convertible Notes, Due 2018 [Member]
Debt Instrument [Line Items]
Deferred Finance Costs, Gross	2,303,000		2,303,000
Carrying Amount, Deferred Financing Fees [Member] | Convertible Notes Payable [Member] | Convertible Notes, Due 2018 [Member]
Debt Instrument [Line Items]
Deferred Finance Costs, Gross	$ 4,974,000		$ 4,974,000