CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Property and equipment, Accumulated depreciation	$ 59.8	$ 59.4
Common stock, shares authorized (in shares)	180,000,000	180,000,000
Common stock, issued (in shares)	74,342,826	74,342,826
Common stock, outstanding (in shares)	72,297,845	74,342,826
Treasury stock (in shares)	2,044,981