Commitments and Contingencies - Narrative (Details) € in Millions							1 Months Ended		3 Months Ended				6 Months Ended	12 Months Ended		54 Months Ended
	Jun. 30, 2018 site	Dec. 31, 2017 USD ($)	Apr. 06, 2017 EUR (€)	Oct. 31, 2016 USD ($)	Mar. 03, 2016 USD ($)	Apr. 11, 2014 USD ($) mi	Oct. 31, 2019 USD ($)	Aug. 31, 2016 residence sampling_event	Mar. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Sep. 30, 2017 USD ($)	Jun. 30, 2020 USD ($) site Potentially_Responsible_Party mi	Dec. 31, 2016 USD ($) site	Dec. 31, 2015 USD ($) site	Jun. 30, 2020 USD ($) site mi	Jan. 31, 2019 property	Jun. 30, 2016 EUR (€)	Oct. 15, 2015 mine	Apr. 30, 2015 USD ($)	Dec. 31, 2014 USD ($)	Feb. 19, 2014 site
Site Contingency
Number of sites subject to remediation (sites) | site													20			20
Number of sites, cost in excess of 100K (sites) | site													17			17
Cost per site minimis threshold													$ 100,000
Number of sites, discontinued operations (sites) | site													18			18
Number of sites, active operations (sites) | site													2			2
Number of sites, investigation completed (sites) | site													16			16
Number of sites investigation in progress (sites) | site													3			3
Number of sites remediation for soil and groundwater contamination (sites) | site													14			14
Environmental										$ 36,000,000.0			$ 19,000,000.0			$ 19,000,000.0
Portion of site subject to remediation (miles) | mi						8
Number of other potentially responsible parties	120												70
Estimate of cost																				$ 726,000,000
Estimate low end				$ 165,000,000
Estimated development time				4 years
Investigate sites notice from EPA (sites) | site														6
Provision for new losses											$ 1,000,000.0	$ 1,900,000		$ 1,100,000	$ 1,100,000
Investigative sites (sites) | site														8
Accrual component amount													$ 1,100,000			1,100,000
Number of residences above applicable screening levels (residences) | residence								3
Number of sampling events below applicable screening levels | sampling_event								2
Loss contingency percentage of damages allocated to company (percent)			65.00%
Loss contingency percentage of damages allocated to counterparty (percent)			35.00%
Estimate of possible loss | €																		€ 0.4
Estimated insurance recoveries													25,000,000			25,000,000
Insurance recoveries to date													22,000,000
Estimated recovery for non-GST Trust claimants													10,000,000			10,000,000
Threshold of recovery before shared in trust													3,000,000			3,000,000
Coltec Industries Inc.
Site Contingency
Environmental													4,100,000	$ 1,300,000		4,100,000
Provision for new losses		$ 5,700,000									$ 3,500,000
Payments for environmental loss contingencies									$ 4,500,000
Lower passaic river study area, focused feasibility study, April 11, 2014
Site Contingency
Environmental													$ 2,700,000			$ 2,700,000					$ 3,500,000
Minimum
Site Contingency
Site contingency, loss exposure in excess of accrual best estimate | €			€ 1.8
Loss exposure in excess of accrual | €			7.9
Estimate of possible loss | €			5.1
Loss accrual | €			0.4
Minimum | Lower passaic river study area, focused feasibility study, April 11, 2014
Site Contingency
Site contingency, loss exposure in excess of accrual best estimate					$ 1,380,000,000	$ 953,000,000
Maximum
Site Contingency
Portion of site subject to remediation (miles) | mi													9			9
Site contingency, loss exposure in excess of accrual best estimate | €			2.1
Loss exposure in excess of accrual | €			10.2
Estimate of possible loss | €			€ 6.6
Maximum | Lower passaic river study area, focused feasibility study, April 11, 2014
Site Contingency
Site contingency, loss exposure in excess of accrual best estimate					$ 1,730,000,000
Arizona
Site Contingency
Investigate sites notice from EPA (sites)															2				6			2
Mississippi
Site Contingency
Provision for new losses							$ 3,000,000.0			$ 4,700,000
Number of property owners (property) | property																	27
Environmental Remediation
Site Contingency
Loss in period																$ 800,000
Asbestos Issue
Site Contingency
Insurance coverage amount													$ 5,500,000			5,500,000
Insurance available for future claims													5,500,000			5,500,000
Estimated insurance recoveries, current year													1,200,000			1,200,000
Asbestos Issue | GST, LLC
Site Contingency
Insurance recoveries from insolvent carriers													$ 8,800,000			$ 8,800,000
Affiliated Entity | Crucible Steel Corporation
Site Contingency
Portion of site subject to remediation (miles) | mi													17			17