CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Statement of Financial Position [Abstract]
Property and equipment, Accumulated depreciation	$ 61.3	$ 60.3
Common stock, shares authorized	180,000,000	180,000,000
Common stock, issued	92,332,565	92,322,905
Common stock, outstanding	75,329,557	92,302,636
Treasury stock, shares	17,003,008	20,269