Fair Value Measurements (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2012	Dec. 31, 2011
Assets:
Short-term investments	$ 25.5	$ 26.5
Deferred compensation assets	3.6	3.3
Foreign currency contracts	0.5
Total assets at fair value	29.6	29.8
Liabilities:
Contingent consideration	2.5	2.1
Deferred compensation liabilities	6.0	4.6
Interest rate swap contracts	8.6	8.8
Long-term debt	299.3	279.2
Total liabilities at fair value	316.4	294.7
Level 3 Fair Value Measurements [Roll Forward]
Balance, beginning of period	2.1
Increase in fair value recorded in earnings	0.4
Balance, end of period	2.5
Other Financial Instruments [Abstract]
Long-term debt	296.4	299.3
Level 1 [Member]
Assets:
Short-term investments	25.5	26.5
Deferred compensation assets	3.6	3.3
Foreign currency contracts	0
Total assets at fair value	29.1	29.8
Liabilities:
Contingent consideration	0	0
Deferred compensation liabilities	6.0	4.6
Interest rate swap contracts	0	0
Long-term debt	0	0
Total liabilities at fair value	6.0	4.6
Level 2 [Member]
Assets:
Short-term investments	0	0
Deferred compensation assets	0	0
Foreign currency contracts	0.5
Total assets at fair value	0.5	0
Liabilities:
Contingent consideration	0	0
Deferred compensation liabilities	0	0
Interest rate swap contracts	8.6	8.8
Long-term debt	299.3	279.2
Total liabilities at fair value	307.9	288.0
Level 3 [Member]
Assets:
Short-term investments	0	0
Deferred compensation assets	0	0
Foreign currency contracts	0
Total assets at fair value	0	0
Liabilities:
Contingent consideration	2.5	2.1
Deferred compensation liabilities	0	0
Interest rate swap contracts	0	0
Long-term debt	0	0
Total liabilities at fair value	$ 2.5	$ 2.1