Unconsolidated Affiliate (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Mar. 31, 2016	Dec. 31, 2015
Investment in unconsolidated affiliates
Equity method investment ownership interest (percent)					50.00%
Investment in unconsolidated affiliate	$ 99,000,000		$ 99,000,000			$ 103,200,000
Equity in earnings of unconsolidated affiliate	2,600,000	$ 2,300,000	9,500,000	$ 8,500,000
Summary of Statement of Operations information:
Grace sales of catalysts to ART	43,800,000	63,300,000	100,300,000	117,500,000
Charges for fixed costs, research and development and selling, general and administrative services to ART	6,100,000	$ 5,900,000	12,300,000	$ 11,800,000
Grace
Summary of Statement of Operations information:
Line of credit facility, maximum provided by Grace and Chevron each	15,000,000.0		$ 15,000,000.0
Commitment fee on credit facility (as a percent)			0.10%
Credit facility amount outstanding	0		$ 0
Chevron
Summary of Statement of Operations information:
Line of credit facility, maximum provided by Grace and Chevron each	$ 15,000,000.0		$ 15,000,000.0
Commitment fee on credit facility (as a percent)			0.10%
Credit facility amount outstanding						$ 0