Other Comprehensive Income (Loss) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Defined benefit pension and other postretirement plans:
Amortization of net prior service cost included in net periodic benefit cost	$ 0.7	$ 0.8	$ 1.1
Other Comprehensive Income, Amortization of Defined Benefit Plan, Net Deferred Actuarial Gain (Loss) Recognized in Net Periodic Benefit Cost before Tax	0.4	0.6	0.6
Net prior service credit arising during period	1.7		0.4
Net deferred actuarial loss arising during period	4.3	2.1	7.3
Benefit plans, net	7.1	3.5	9.4
Currency translation adjustments	(23.6)	5.5	(11.3)
Gain (loss) from hedging activities	(0.3)	3.7	(3.2)
Other comprehensive income (loss) attributable to W. R. Grace and Co. shareholders	(16.7)	12.7	(5.1)
Defined benefit pension and other postretirement plans:
Amortization of net prior service credit included in net periodic benefit cost	(0.2)	(0.3)	(0.4)
Amortization of net deferred actuarial loss included in net periodic benefit cost	(0.1)	(0.2)	(0.2)
Net prior service credit arising during period	(0.6)		(0.1)
Net deferred actuarial loss arising during period	(1.6)	(0.7)	(2.5)
Benefit plans, net	(2.5)	(1.2)	(3.2)
Currency translation adjustments	0	0	0
Gain (loss) from hedging activities	0.1	(1.3)	1.1
Other comprehensive income (loss) attributable to W. R. Grace and Co. shareholders	(2.4)	(2.5)	(2.1)
Defined benefit pension and other postretirement plans:
Amortization of net prior service credit included in net periodic benefit cost	0.5	0.5	0.7
Amortization of net deferred actuarial loss included in net periodic benefit cost	0.3	0.4	0.4
Net prior service credit arising during period	1.1		0.3
Net deferred actuarial loss arising during period	2.7	1.4	4.8
Benefit plans, net	4.6	2.3	6.2
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax, Portion Attributable to Parent	(23.6)	5.5	(11.3)
Gain (loss) from hedging activities	(0.2)	2.4	(2.1)
Other comprehensive income (loss) attributable to W. R. Grace & Co. shareholders	(19.1)	10.2	(7.2)
Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, before Tax	0.1
Other Comprehensive Income (Loss), Available-for-sale Securities, Tax	0
Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax	$ 0.1