Consolidated Balance Sheets (Parenthetical) (USD $) In Millions, except Share data, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Statement of Financial Position [Abstract]
Trade accounts receivable, allowance	$ 6.4	$ 6.0
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment and Capitalized Computer Software, Total	$ 1,921.7	$ 1,876.8
Common stock issued, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock issued, shares authorized	300,000,000	300,000,000
Common stock issued, shares outstanding	75,145,799	77,046,143
Treasury stock, shares	2,301,449	0