Commitments and Contingent Liabilities (Details) $ in Millions	6 Months Ended		12 Months Ended
	Jun. 30, 2015 USD ($) payment claim shares	Jun. 30, 2014 USD ($)	Dec. 31, 2010 facility	Dec. 31, 2014 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	$ 28.7			$ 28.2
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
PD Claims Accrual Post Effective Date	$ 0.4
PD Claims Filed After Effective Date | claim	2
Number of Shares Issuable under Warrant | shares	77,372,257
Environmental remediation
Estimated liability for environmental investigative and remediation costs	$ 53.5			61.7
Net cash expenditures	5.6	$ 7.0
Vermiculite Related Matters
Environmental remediation
Estimated liability for environmental investigative and remediation costs	13.4			19.4
Maximum number of operating plants under U.S. Environmental Protection Agency (EPA) reinvestigation | facility			105
Non-Vermiculite Related Matters
Environmental remediation
Estimated liability for environmental investigative and remediation costs	$ 40.1			$ 42.3