Unconsolidated Affiliates (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Equity Method Investments and Joint Ventures [Abstract]
Equity method investment, ownership interest	50.00%
Investment in unconsolidated affiliate	$ 85.5	$ 70.8
Equity in earnings of unconsolidated affiliates	18.5	15.2	17.8
ART's assets, liabilities and results of operations:
Current assets	136.7	136.6
Noncurrent assets	65.9	46.4
Total assets	202.6	183.0
Current liabilities	37.8	48.1
Noncurrent liabilities	0.1
Total liabilities	37.9	48.1
Net sales	325.0	339.0	308.2
Costs and expenses applicable to net sales	276.0	296.3	262.6
Income before income taxes	38.9	32.8	37.3
Net income	37.8	31.2	35.7
Related party transactions:
Grace sales of catalysts to ART	206.9	171.4	211.0
Charges for fixed costs, research and development and selling, general and administrative services to ART	28.5	27.8	24.5
Schedule of Investments [Line Items]
Commitment fee on credit facility	0.10%
W R Grace & Co. [Member]
Schedule of Investments [Line Items]
Line of credit facility, maximum provided by Grace and Chevron each	$ 15