Earnings Per Share - Basic and Diluted Loss Per Share (Detail) - shares shares in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Earnings Per Share [Abstract]
Basic weighted average common shares outstanding	88.3	89.2	89.8
Add: Dilutive impact of outstanding equity awards	0.7	0.7	0.9
Diluted weighted average common shares outstanding	89.0	89.9	90.7