Income Taxes - Rate Reconciliation (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Income before income taxes	$ 127.4	$ 105.1	$ 101.5
Statutory taxes at 35.0%	44.6	36.8	35.5
Valuation allowance	(12.1)	(19.7)	(9.9)
Foreign statutory rate differences	(11.4)	(9.9)	(8.7)
Equity interest earnings	(1.2)	(1.6)	(1.9)
Unremitted foreign earnings	(1.2)	(1.1)	1.5
R&D and other federal credits	(2.4)	(0.7)	(0.7)
State income taxes	2.0	2.0	2.6
Non-deductible expenses	0.3	0.8	0.7
Tax controversy resolution	(1.8)	0.1	0.1
Other	0.4	0.3	(0.3)
Income tax provision	$ 17.2	$ 7.0	$ 18.9
Effective income tax rate	13.50%	6.70%	18.60%