Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Statement Of Financial Position [Abstract]
Property, plant and equipment, accumulated depreciation and amortization	$ 421.8	$ 412.9
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares issued	61,717,806	61,553,724
Common stock, shares outstanding	48,640,635	48,808,239
Treasury stock, shares	13,077,171	12,745,485