Commitments and Contingent Liabilities - Asbestos-Related Liabilities (Details) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2016 USD ($) payment shares	Mar. 31, 2015 USD ($)	Dec. 31, 2010 facility	Dec. 31, 2015 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
Deferred payment obligation	$ 29.3			$ 29.1
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
Frequency of PD trust payments	6 months
Number of shares issuable under warrant (in shares) | shares	77,372,257
Environmental remediation
Estimated liability for environmental investigative and remediation costs	$ 56.1			55.2
Net cash expenditures	1.4	$ 4.2
Vermiculite Related Matters [Member]
Environmental remediation
Estimated liability for environmental investigative and remediation costs	17.4			18.7
Maximum number of operating plants under U.S. Environmental Protection Agency (EPA) reinvestigation | facility			105
Non-Vermiculite Related Matters [Member]
Environmental remediation
Estimated liability for environmental investigative and remediation costs	$ 38.7			$ 36.5