Unconsolidated Affiliate (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Equity Method Investments and Joint Ventures [Abstract]
Equity method investment ownership interest (percent)	50.00%		50.00%
Investment in unconsolidated affiliate	$ 118,000,000		$ 118,000,000		$ 117,600,000
Equity in earnings of unconsolidated affiliate	4,800,000	$ 8,500,000	17,900,000	$ 18,000,000
ART's assets, liabilities and results of operations
Current assets	268,500,000		268,500,000		249,200,000
Noncurrent assets	85,500,000		85,500,000		84,800,000
Total assets	354,000,000		354,000,000		334,000,000
Current liabilities	121,700,000		121,700,000		102,000,000
Noncurrent liabilities					300,000
Total liabilities	121,700,000		121,700,000		102,300,000
Net sales	113,500,000	110,100,000	321,400,000	255,800,000
Costs and expenses applicable to net sales	100,100,000	89,800,000	273,700,000	213,200,000
Income before income taxes	10,400,000	18,200,000	37,200,000	37,400,000
Net income	9,600,000	17,000,000	35,800,000	35,900,000
Related Party Transactions [Abstract]
Grace sales of catalysts to ART	54,500,000	56,100,000	159,000,000	156,400,000
Mark-up on Grace's sales to ART included as a reduction of Grace's cost of goods sold	1,100,000	1,100,000	3,100,000	3,100,000
Charges for fixed costs, research and development, selling, general and administrative services, and depreciation to ART	10,400,000	$ 6,200,000	31,200,000	$ 18,500,000
Investment in unconsolidated affiliates
Accounts receivable	14,500,000		14,500,000		14,900,000
Noncurrent asset	28,000,000		28,000,000		27,000,000
Accounts payable	24,500,000		24,500,000		28,700,000
Debt payable within one year	7,700,000		7,700,000		7,600,000
Debt payable after one year	33,700,000		33,700,000		31,900,000
Liability to unconsolidated affiliate	28,000,000		28,000,000		27,000,000
Grace
Investment in unconsolidated affiliates
Line of credit facility, maximum provided by Grace and Chevron each	15,000,000.0		$ 15,000,000.0
Commitment fee on credit facility (as a percent)			0.10%
Credit facility amount outstanding	0		$ 0		$ 0
Chevron
Investment in unconsolidated affiliates
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%