Supplemental Cash Flow Information (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Supplemental disclosure of cash flow information:
Interest paid	$ 28.1	$ 19.4	$ 10.4
Income taxes paid	2.1	1.8	3.5
Supplemental disclosure of non-cash transactions:
Stock repurchases not yet settled (accrued in accounts payable)	1.0	0	0
Non-cash capital expenditures	4.4	3.4	1.8
Capital leases acquired	$ 0.2	$ 0.1	$ 0.3