Acquisitions (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012 Y	Dec. 31, 2011	Jul. 28, 2011
Acquisitions [Abstract]
Business acquisition, cash paid			$ 10.6
Fair value of contingent consideration	1.1	1.0	0.9
Potential cash payment to shareholders	$ 12.0
Contingent consideration expiration year	2015
Period for performance evaluation, years	4
Business acquisition, effective date	Jul. 28, 2011