Unconsolidated Affiliate (Details) - USD ($)	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Equity Method Investments and Joint Ventures [Abstract]
Equity method investment ownership interest (percent)	50.00%
Investment in unconsolidated affiliate	$ 132,200,000		$ 125,900,000
Equity in earnings of unconsolidated affiliate	5,400,000	$ 7,000,000
ART's assets, liabilities and results of operations
Current assets	241,900,000		239,800,000
Noncurrent assets	100,900,000		91,500,000
Total assets	342,800,000		331,300,000
Current liabilities	81,500,000		82,400,000
Noncurrent liabilities	300,000		300,000
Total liabilities	81,800,000		82,700,000
Net sales	85,200,000	97,400,000
Costs and expenses applicable to net sales	70,700,000	78,900,000
Income before income taxes	11,300,000	14,200,000
Net income	11,500,000	14,000,000
Related Party Transactions [Abstract]
Product manufactured for ART	51,900,000	51,400,000
Mark-up on product manufactured for ART included as a reduction of Grace’s cost of goods sold	1,000,000	1,000,000
Charges for fixed costs; research and development; selling, general and administrative services; and depreciation to ART	10,700,000	$ 10,400,000
Investment in unconsolidated affiliates
Accounts receivable	19,700,000		20,100,000
Noncurrent asset	38,500,000		32,700,000
Accounts payable	27,900,000		22,300,000
Debt payable within one year	8,900,000		8,600,000
Debt payable after one year	36,700,000		33,800,000
Liability to unconsolidated affiliate	38,500,000		32,700,000
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%