Unconsolidated Affiliate (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 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	$ 131,900,000		$ 131,900,000		$ 117,600,000
Equity in earnings of unconsolidated affiliate	6,100,000	$ 2,600,000	13,100,000	$ 9,500,000
ART's assets, liabilities and results of operations
Current assets	246,700,000		246,700,000		249,200,000
Noncurrent assets	84,900,000		84,900,000		84,800,000
Total assets	331,600,000		331,600,000		334,000,000
Current liabilities	71,700,000		71,700,000		102,000,000
Noncurrent liabilities					300,000
Total liabilities	71,700,000		71,700,000		102,300,000
Net sales	110,500,000	81,700,000	207,900,000	145,700,000
Costs and expenses applicable to net sales	94,700,000	75,200,000	173,600,000	123,400,000
Income before income taxes	12,600,000	5,300,000	26,800,000	19,200,000
Net income	12,200,000	5,100,000	26,200,000	18,900,000
Related Party Transactions [Abstract]
Grace sales of catalysts to ART	53,100,000	43,800,000	104,500,000	100,300,000
Mark-up on Grace's sales to ART included as a reduction of Grace's cost of goods sold	1,000,000	1,100,000	2,000,000	2,000,000
Charges for fixed costs, research and development, selling, general and administrative services, and depreciation to ART	10,400,000	$ 6,100,000	20,800,000	$ 12,300,000
Investment in unconsolidated affiliates
Accounts receivable	3,300,000		3,300,000		14,900,000
Noncurrent asset	27,400,000		27,400,000		27,000,000
Accounts payable	28,800,000		28,800,000		28,700,000
Debt payable within one year	7,800,000		7,800,000		7,600,000
Debt payable after one year	32,200,000		32,200,000		31,900,000
Liability to unconsolidated affiliate	27,400,000		27,400,000		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%