Earnings Per Share - Schedule of Computation of Basic and Diluted Earnings Per Share (Detail) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Numerator (basic and diluted):
Income from continuing operations attributable to EnPro Industries, Inc.	$ 10.1	$ 7.8
Income from discontinued operations	208.6	5.3
Net income attributable to EnPro Industries, Inc.	$ 218.7	$ 13.1
Denominator:
Weighted-average shares – basic (in shares)	20.6	20.8
Share-based awards (in shares)	0.0	0.1
Weighted-average shares – diluted (in shares)	20.6	20.9
Basic earnings per share attributable to EnPro Industries, Inc.:
Continuing operations (in dollars per share)	$ 0.49	$ 0.37
Discontinued operations (in dollars per share)	10.13	0.26
Net income per share (in dollars per share)	10.62	0.63
Diluted earnings per share attributable to EnPro Industries, Inc.:
Continuing operations (in dollars per share)	0.49	0.37
Discontinued operations (in dollars per share)	10.10	0.26
Net income per share (in dollars per share)	$ 10.59	$ 0.63