Subsequent Events (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended
	Mar. 31, 2013	Dec. 31, 2012	Feb. 27, 2013	Dec. 31, 2011
Subsequent Event [Line Items]
Legal claim settlement	$ 1.5
Amount originally accrued for legal claim		0.8
Additional amount accrued for legal claim		0.7
Percentage of equity interest (in hundredths)		19.90%	19.90%
Sale of equity interest in a company	3.2
Book value of investment at the date of sale		1.7	1.6	1.2
Realized gains on disposal, equity method investment	$ 1.6