Defendant Asbestos and Environmental Liabilities - Additional Information (Details) $ in Millions	Dec. 31, 2019 USD ($) site	Dec. 31, 2018 USD ($)
Liability for Claims and Claims Adjustment Expense [Line Items]
Asbestos and environmental liabilities	$ 2,259.6	$ 1,839.7
Number of hazardous waste disposal sites \| site	22
Defendant asbestos liabilities
Liability for Claims and Claims Adjustment Expense [Line Items]
Asbestos and environmental liabilities	$ 1,100.6	266.0
Defendant environmental liabilities
Liability for Claims and Claims Adjustment Expense [Line Items]
Asbestos and environmental liabilities	$ 10.3	$ 2.2

Carrying amount as of the balance sheet date of reserves for the costs of settling insured claims and costs incurred in the claims settlement process attributable to asbestos and environmental claims, before estimated recoveries from reinsurers.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 40
-Section 50
-Paragraph 3
-Subparagraph (cc)
-URI http://asc.fasb.org/extlink&oid=116884095&loc=d3e14764-158437

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 40
-Section 50
-Paragraph 3
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=116884095&loc=d3e14764-158437

Name:	us-gaap_LiabilityForAsbestosAndEnvironmentalClaimsGross
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant