Debt (Details) In Millions, except Per Share data, unless otherwise specified	12 Months Ended					12 Months Ended		12 Months Ended		12 Months Ended			12 Months Ended			2 Months Ended	12 Months Ended					12 Months Ended		1 Months Ended	12 Months Ended
	Dec. 31, 2011 USD ($)	Dec. 31, 2010 USD ($)	Dec. 31, 2009 USD ($)	Dec. 31, 2011 Capital Leases [Member] USD ($)	Dec. 31, 2010 Capital Leases [Member] USD ($)	Dec. 31, 2011 Series A Floating Rate Notes Due 2012 [Member] USD ($)	Dec. 31, 2010 Series A Floating Rate Notes Due 2012 [Member] USD ($)	Dec. 31, 2011 Series B Floating Rate Notes Due 2015 [Member] USD ($)	Dec. 31, 2010 Series B Floating Rate Notes Due 2015 [Member] USD ($)	Dec. 31, 2011 EURO Note A Due 2013 [Member] USD ($)	Dec. 31, 2011 EURO Note A Due 2013 [Member] EUR (€)	Dec. 31, 2010 EURO Note A Due 2013 [Member] USD ($)	Dec. 31, 2011 EURO Note B Due 2016 [Member] USD ($)	Dec. 31, 2011 EURO Note B Due 2016 [Member] EUR (€)	Dec. 31, 2010 EURO Note B Due 2016 [Member] USD ($)	Apr. 30, 2007 Convertible Debt Due 2047 [Member] USD ($)	Dec. 31, 2011 Convertible Debt Due 2047 [Member] USD ($)	Dec. 31, 2010 Convertible Debt Due 2047 [Member] USD ($)	Dec. 31, 2011 Floating Rate Notes [Member] USD ($)	Dec. 31, 2011 EURO Note [Member] EUR (€)	Dec. 31, 2011 Term Loan Due 2014 [Member] USD ($)	Dec. 31, 2011 Revolving Credit Facility Due 2014 [Member] USD ($)	Jun. 30, 2010 Revolving Credit Facility Due 2014 [Member] USD ($)	Jun. 30, 2010 Prior Credit Facility [Member] USD ($)	Dec. 31, 2011 $50 Million Credit Facility [Member] USD ($)
Debt Disclosure [Abstract]
Notes payable and other current debt	$ 50.1	$ 0.3
Total debt	349.4	358.4
Line of Credit Facility [Line Items]
Line of credit facility, current borrowing capacity																						225.0
Basis spread on variable interest rate, maximum (in hundredths)																						2.75%			1.50%
Line of credit facility capacity, maximum																						275.0			50.0
Credit facility agreement, interest coverage ratio description																									interest coverage ratio greater than or equal to 2.50 to 1.00
Credit facility agreement, leverage ratio description																									total leverage ratio no greater than 3.50 to 1.00
Line of credit facility swing-line loans, maximum																						20.0
Line of credit facility, Maximum amount available for the issuance of standby letters of credit																						20.0
Variable rate basis						LIBOR		LIBOR														LIBOR			one-month LIBOR
Basis spread on variable interest rate, minimum (in hundredths)																						1.75%
Debt covenant, total indebtedness to earnings before income tax, maximum																						Under the leverage ratio, our total indebtedness cannot exceed three-and one-half (3.5) times our earnings before income tax, depreciation and amortization for any period of four consecutive quarters
Extinguishment of debt																								26.6
Debt issuance costs																5.2							1.7		0.3
Quarterly commitment fee, minimum (in hundredths)																						0.325%
Quarterly commitment fee, maximum (in hundredths)																						0.55%
Letters of credit outstanding																						3.3
Unused commitment level																						215.3
Interest rate (in hundredths)						1.20%		1.30%		4.20%	4.20%		4.40%	4.40%			4.00%				8.40%	2.10%
Line of credit facility, expiration date																						2014
Debt Instrument [Line Items]
Debt instrument, Face amount						50.0		25.0		26.3	20.4		79.0	61.1					75.0	81.5
Tranches of private placement of notes	2
Long-term debt	299.3	358.1				50.0	50.0	25.0	25.0	26.3		27.0	79.0		81.0		161.5	161.5			0.2
Interest rate, minimum (in hundredths)				5.30%
Interest rate, maximum (in hundredths)				6.00%
Term of debt (in years)										7 years	7 years		10 years	10 years
Stated interest rate (in hundredths)						1.20%		1.30%		4.20%	4.20%		4.40%	4.40%			4.00%				8.40%	2.10%
Convertible debt, conversion price (in dollars per share)																	$ 55.44
Conversion ratio of debt per $1,000 of debt																	18.0386
Debentures automatic conversion feature																	On or after March 20, 2012, if our common stock closing price exceeds 150% of the then prevailing conversion price for at least 20 trading days during any 30 consecutive trading day period, we have the option to cause the debentures to be automatically converted into West shares at the prevailing conversion rate.
Net proceeds from the offering of convertible debt																156.3
Interest expense	19.3	17.7	17.6
Capital leases				1.0	1.7
Line of credit facility, amount outstanding	6.4	12.2
Long-term debt	299.3	358.1				50.0	50.0	25.0	25.0	26.3		27.0	79.0		81.0		161.5	161.5			0.2
Debt instrument, maturity date						Jul. 28, 2012		Jul. 28, 2015		Feb. 27, 2013	Feb. 27, 2013		Feb. 27, 2016	Feb. 27, 2016			Mar. 15, 2047
Variable rate basis						LIBOR		LIBOR														LIBOR			one-month LIBOR
Basis spread on variable interest rate, maximum (in hundredths)						0.80%		0.90%
Debt issuance costs																5.2							1.7		0.3
Aggregate annual maturities of long-term debt [Abstract]
2013	26.7
2014	6.6
2015	25.0
2016	79.5
Thereafter	$ 161.5