Accumulated Other Comprehensive Loss - Summary of Changes in Accumulated Other Comprehensive Loss by Component (Detail) - USD ($) $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2020	Jun. 30, 2019
Accumulated Other Comprehensive Income
Other comprehensive income (loss) before reclassifications	$ 22.4		$ (4.0)		$ 0.3	$ 1.8
Amounts reclassified from accumulated other comprehensive loss	0.9		1.4		1.4	2.4
Net current-period other comprehensive income	23.3		(2.6)		1.7	4.2
Unrealized Translation Adjustments
Accumulated Other Comprehensive Income
Beginning balance	(13.2)	$ 9.8	(4.8)	$ (10.6)	9.8	(10.6)
Other comprehensive income (loss) before reclassifications	22.4		(4.0)		0.3	1.8
Amounts reclassified from accumulated other comprehensive loss	0.0		0.0		0.0	0.0
Net current-period other comprehensive income	22.4		(4.0)		0.3	1.8
Less: other comprehensive income attributable to redeemable non-controlling interests	0.6				1.5
Net current-period other comprehensive income attributable to EnPro Industries, Inc.	21.8				(1.2)
Ending balance	8.6	(13.2)	(8.8)	(4.8)	8.6	(8.8)
Unrealized Translation Adjustments | Cumulative Effect, Period of Adoption, Adjustment
Accumulated Other Comprehensive Income
Beginning balance				0.0		0.0
Unrealized Translation Adjustments | Cumulative Effect, Period of Adoption, Adjusted Balance
Accumulated Other Comprehensive Income
Beginning balance				(10.6)		(10.6)
Pension and Other Postretirement Plans
Accumulated Other Comprehensive Income
Beginning balance	(45.7)	(46.2)	(45.4)	(34.9)	(46.2)	(34.9)
Other comprehensive income (loss) before reclassifications	0.0		0.0		0.0	0.0
Amounts reclassified from accumulated other comprehensive loss	0.9		1.4		1.4	2.4
Net current-period other comprehensive income	0.9		1.4		1.4	2.4
Less: other comprehensive income attributable to redeemable non-controlling interests	0.0				0.0
Net current-period other comprehensive income attributable to EnPro Industries, Inc.	0.9				1.4
Ending balance	(44.8)	(45.7)	(44.0)	(45.4)	(44.8)	(44.0)
Pension and Other Postretirement Plans | Cumulative Effect, Period of Adoption, Adjustment
Accumulated Other Comprehensive Income
Beginning balance				(11.5)		(11.5)
Pension and Other Postretirement Plans | Cumulative Effect, Period of Adoption, Adjusted Balance
Accumulated Other Comprehensive Income
Beginning balance				(46.4)		(46.4)
Accumulated Other Comprehensive Loss
Accumulated Other Comprehensive Income
Beginning balance	(58.9)	(36.4)	(50.2)	(45.5)	(36.4)	(45.5)
Net current-period other comprehensive income	22.7	(22.5)	(2.6)	6.8
Less: other comprehensive income attributable to redeemable non-controlling interests	0.6				1.5
Net current-period other comprehensive income attributable to EnPro Industries, Inc.	22.7				0.2
Ending balance	$ (36.2)	$ (58.9)	$ (52.8)	(50.2)	$ (36.2)	(52.8)
Accumulated Other Comprehensive Loss | Cumulative Effect, Period of Adoption, Adjustment
Accumulated Other Comprehensive Income
Beginning balance				(11.5)		(11.5)
Accumulated Other Comprehensive Loss | Cumulative Effect, Period of Adoption, Adjusted Balance
Accumulated Other Comprehensive Income
Beginning balance				$ (57.0)		$ (57.0)