CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $) In Millions, except Share data, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Statement of Financial Position [Abstract]
Trade accounts receivable, allowance for doubtful accounts	$ 4.7	$ 4.6
Acquisition intangibles, accumulated amortization	$ 61.5	$ 58.0
Preferred stock, shares authorized	20,000,000	20,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	150,000,000	150,000,000
Common stock, shares issued	49,833,711	49,725,752
Treasury stock, shares	13,998,624	14,221,374