Earnings Per Share (Tables)

12 Months Ended

Dec. 31, 2015

Earnings Per Share [Abstract]

Schedule of reconciliation of the numerators and denominators used in calculating basic and diluted earnings per share

The following table shows a reconciliation of the numerators and denominators used in calculating basic and diluted earnings per share.

(In millions, except per share amounts)	2015		2014		2013
Numerators
Net income attributable to W. R. Grace & Co. shareholders	$	144.2	$	276.3	$	256.1
Denominators
Weighted average common shares—basic calculation	72.0		75.3		76.4
Dilutive effect of employee stock options	0.6		0.9		1.3
Weighted average common shares—diluted calculation	72.6		76.2		77.7
Basic earnings per share	$	2.00	$	3.67	$	3.35
Diluted earnings per share	$	1.99	$	3.63	$	3.30