Operating Segment Information (Details) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2015 USD ($)	Sep. 30, 2015 USD ($)	Jun. 30, 2015 USD ($)	Mar. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Sep. 30, 2014 USD ($)	Jun. 30, 2014 USD ($)	Mar. 31, 2014 USD ($)	Dec. 31, 2015 USD ($) segment	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Operating segment information
Number of operating segments | segment									3
Net Sales
Net sales	$ 758.7	$ 790.1	$ 782.1	$ 720.6	$ 804.1	$ 856.4	$ 838.0	$ 744.5	$ 3,051.5	$ 3,243.0	$ 3,060.7
Adjusted EBIT
Gain on termination of postretirement plans related to current businesses									1.9	23.6	0.0
Certain Pension Costs									25.5	32.0	27.4
Grace Adjusted EBIT									618.5	626.2	550.8
Depreciation and Amortization									131.5	137.1	123.1
Capital Expenditures									154.8	169.8	156.2
Total Assets	3,676.0				4,093.6				3,676.0	4,093.6	5,390.1
Reconciliation of operating segment data to financial statements
Grace Adjusted EBIT									618.5	626.2	550.8
Interest expense, net									(100.4)	(125.8)	(42.8)
Currency and other losses in Venezuela									73.2	1.0	6.9
Repositioning expenses									(64.3)	0.0	0.0
Restructuring expenses and asset impairments									(22.9)	(22.4)	(12.5)
Pension MTM adjustment and other related costs, net									(46.8)	(128.3)	50.6
Costs related to Chapter 11 and asbestos, net									5.6	26.3	46.1
Gain on termination and curtailment of postretirement plans related to divested businesses									2.6	15.9	0.0
Income and expense items related to divested businesses									1.0	(5.2)	(4.1)
Gain (loss) on sale of product line										0.2	(1.0)
Default interest settlement									0.0	0.0	(129.0)
Net income attributable to noncontrolling interests									(0.7)	(1.0)	(1.6)
Income before income taxes									309.6	334.3	360.6
Catalysts Technologies
Net Sales
Net sales									1,162.1	1,246.8	1,124.0
Adjusted EBIT
Operating income (loss)									347.3	378.3	327.5
Depreciation and Amortization									68.1	66.3	54.2
Capital Expenditures									66.3	81.6	58.7
Total Assets	1,390.8				1,395.4				1,390.8	1,395.4	1,361.8
Materials Technologies
Net Sales
Net sales									797.0	890.6	878.5
Adjusted EBIT
Operating income (loss)									177.5	185.2	181.8
Depreciation and Amortization									28.4	32.1	31.4
Capital Expenditures									25.8	35.6	33.0
Total Assets	464.1				501.2				464.1	501.2	508.9
Construction Products
Net Sales
Net sales									1,092.4	1,105.6	1,058.2
Adjusted EBIT
Operating income (loss)									196.6	161.7	151.7
Depreciation and Amortization									28.6	31.7	31.8
Capital Expenditures									31.0	28.3	32.8
Total Assets	536.0				580.0				536.0	580.0	609.1
Corporate costs
Adjusted EBIT
Operating income (loss)									(79.3)	(90.6)	(82.8)
Corporate [Member]
Adjusted EBIT
Depreciation and Amortization									6.4	7.0	5.7
Capital Expenditures									31.7	24.3	31.7
Total Assets	$ 1,285.1				$ 1,617.0				$ 1,285.1	$ 1,617.0	$ 2,910.3