Commitments and Contingent Liabilities - Asbestos-Related Liabilities (Details) $ in Millions	3 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2017 USD ($) shares	Sep. 30, 2017 USD ($) payment shares	Dec. 31, 2016 USD ($)	Feb. 03, 2017 USD ($)	Feb. 03, 2014 USD ($)
Other Commitments Chapter 11 [Abstract]
ZAI PD account funding					$ 34.4
ZAI P D Account, Payment on Third Anniversary of Effective Date of Joint Plan				$ 30.0
ZAI P D account, maximum number of contingent deferred payments | payment		10
ZAI P D account, deferred payments, each year for twenty years		$ 8.0
Period in which ZAI PD contingent deferred payments will be made		20 years
Minimum ZAI P D account assets for condition in relation to contingent obligation payments	$ 10.0	$ 10.0
Frequency of PD trust payments		6 months
Estimated annual expenses related to PD Trust			$ 0.2
Number of shares issuable under warrant (in shares) | shares	77,372,257	77,372,257
Environmental remediation
Estimated liability for environmental investigative and remediation costs	$ 70.6	$ 70.6	66.3
Vermiculite Related Matters [Member]
Environmental remediation
Accrual for Environmental Investigative and Remediation Costs, Period Increase (Decrease)	0.5
Estimated liability for environmental investigative and remediation costs	25.1	25.1	31.2
Non-Vermiculite Related Matters [Member]
Environmental remediation
Accrual for Environmental Investigative and Remediation Costs, Period Increase (Decrease)	5.9
Estimated liability for environmental investigative and remediation costs	$ 45.5	$ 45.5	$ 35.1