Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Jun. 30, 2016	Dec. 31, 2015
Statement Of Financial Position [Abstract]
Property, plant and equipment, accumulated depreciation and amortization	$ 430.0	$ 403.8
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares issued	60,542,365	60,416,446
Common stock, shares outstanding	55,484,983	55,359,064
Treasury stock, shares	5,057,382	5,057,382