Consolidated Statements of Operations - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenues	$ 1,932.1	$ 1,716.5	$ 1,598.6
Cost of goods sold	1,165.4	1,040.4	928.8
Gross profit	766.7	676.1	669.8
Selling, general and administrative expenses	307.0	274.0	271.8
Research and development expenses	62.7	56.3	51.6
Provision for environmental remediation	73.8	24.4	28.7
Restructuring and repositioning expenses	46.4	26.7	38.6
Equity in earnings of unconsolidated affiliate	(31.8)	(25.9)	(29.8)
Interest expense and related financing costs	80.2	79.5	81.5
Nonoperating Income (Expense)	16.5	(30.2)	(61.4)
Total costs and expenses	521.8	465.2	503.8
Income (loss) from continuing operations before income taxes	244.9	210.9	166.0
(Provision for) benefit from income taxes	(78.1)	(200.5)	(59.0)
Income (loss) from continuing operations	166.8	10.4	107.0
Income (loss) from discontinued operations, net of income taxes	0.0	0.0	(12.9)
Net income (loss)	166.8	10.4	94.1
Less: Net (income) loss attributable to noncontrolling interests	0.8	0.8	0.0
Net income (loss) attributable to W. R. Grace & Co. shareholders	167.6	11.2	94.1
Net Income (Loss) Available to Common Stockholders, Basic [Abstract]
Income (loss) from continuing operations attributable to W. R. Grace & Co. shareholders	$ 167.6	$ 11.2	$ 107.0
Basic earnings per share attributable to W. R. Grace & Co. shareholders
Income (loss) from continuing operations	$ 2.49	$ 0.16	$ 1.53
Income (loss) from discontinued operations, net of income taxes	0.00	0.00	(0.19)
Net income (loss)	$ 2.49	$ 0.16	$ 1.34
Weighted average number of basic shares	67.2	68.1	70.1
Diluted earnings per share attributable to W. R. Grace & Co. shareholders
Income (loss) from continuing operations	$ 2.49	$ 0.16	$ 1.52
Income (loss) from discontinued operations, net of income taxes	0.00	0.00	(0.19)
Net income (loss)	$ 2.49	$ 0.16	$ 1.33
Weighted average number of diluted shares	67.3	68.2	70.5
Dividends per common share	$ 0.96	$ 0.84	$ 0.51