Fair Value of Financial Instruments (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010
Assets: [Abstract]
Short-term investments	$ 26.5	$ 0.6
Deferred compensation assets	3.3	3.6
Total assets at fair value	29.8	4.2
Liabilities: [abstract]
Contingent consideration	2.1	2.3
Deferred compensation liabilities	4.6	5.4
Interest rate swap contracts	8.8	6.1
Total Liabilities at Fair Value	15.5	13.8
Other Financial Instruments [Abstract]
Fair value of long-term debt	279.2	344.2
Long-term debt	299.3	358.1
Contingent Consideration [Member]
Level 3 Fair Value Measurements [Roll Forward]
Beginning Balance	2.3	2.8
Additional contingent consideration acquired		1.8
Increase in fair value recorded in earnings	0.5	0.2
Reduction in fair value recorded in earnings	(0.8)	(2.1)
Changes in foreign currency exchange rates	0.1	(0.4)
Ending Balance	2.1	2.3
Fair Value, Inputs, Level 1 [Member]
Assets: [Abstract]
Short-term investments	26.5	0.6
Deferred compensation assets	3.3	3.6
Total assets at fair value	29.8	4.2
Liabilities: [abstract]
Deferred compensation liabilities	4.6	5.4
Total Liabilities at Fair Value	4.6	5.4
Fair Value, Inputs, Level 2 [Member]
Liabilities: [abstract]
Interest rate swap contracts	8.8	6.1
Total Liabilities at Fair Value	8.8	6.1
Fair Value, Inputs, Level 3 [Member]
Liabilities: [abstract]
Contingent consideration	2.1	2.3
Total Liabilities at Fair Value	$ 2.1	$ 2.3