Unconsolidated Affiliate (Details) - USD ($)	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Investment in unconsolidated affiliates
Equity method investment ownership interest (percent)	50.00%
Investment in unconsolidated affiliate	$ 124,900,000		$ 117,600,000
Equity in earnings of unconsolidated affiliate	7,000,000	$ 6,900,000
Net sales	97,400,000	64,000,000
Costs and expenses applicable to net sales	78,900,000	48,200,000
Income before income taxes	14,200,000	13,900,000
Net income	14,000,000	13,800,000
Grace sales of catalysts to ART	51,400,000	56,500,000
Charges for fixed costs, research and development, selling, general and administrative services, and depreciation to ART	10,400,000	$ 6,200,000
Trade accounts receivable	2,100,000		14,900,000
Noncurrent asset	27,000,000		27,000,000
Accounts payable	27,900,000		28,700,000
Debt payable within one year	7,900,000		7,600,000
Debt payable after one year	32,200,000		31,900,000
Liability to unconsolidated affiliate	27,000,000		27,000,000
Grace
Investment in unconsolidated affiliates
Line of credit facility, maximum provided by Grace and Chevron each	$ 15,000,000.0
Commitment fee on credit facility (as a percent)	0.10%
Credit facility amount outstanding	$ 0		$ 0
Chevron
Investment in unconsolidated affiliates
Line of credit facility, maximum provided by Grace and Chevron each	$ 15,000,000.0
Commitment fee on credit facility (as a percent)	0.10%