Other Comprehensive Income (Loss) (Tables)

12 Months Ended

Dec. 31, 2012

Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract]

Tabular disclosure of pre-tax, tax, and after-tax components of other comprehensive income (loss)

The following tables present the pre-tax, tax, and after-tax components of Grace's other comprehensive loss for the years ended December 31, 2012, 2011, and 2010:

Year Ended December 31, 2012 (In millions)	Pre-Tax Amount			Tax Benefit/ (Expense)			After-Tax Amount
Defined benefit pension and other postretirement plans:
Amortization of net prior service cost included in net periodic benefit cost	$	0.8		$	(0.3	)	$	0.5
Amortization of net deferred actuarial loss included in net periodic benefit cost	41.4			(14.2		)	27.2
Net deferred actuarial loss arising during period	(95.4		)	31.1			(64.3		)
Benefit plans, net	(53.2		)	16.6			(36.6		)
Currency translation adjustments	5.4			—			5.4
Gain from hedging activities	3.7			(1.3		)	2.4
Other comprehensive loss attributable to W. R. Grace & Co. shareholders	$	(44.1	)	$	15.3		$	(28.8	)

Year Ended December 31, 2011 (In millions)	Pre-Tax Amount			Tax Benefit/ (Expense)			After-Tax Amount
Defined benefit pension and other postretirement plans:
Amortization of net prior service cost included in net periodic benefit cost	$	1.1		$	(0.4	)	$	0.7
Amortization of net deferred actuarial loss included in net periodic benefit cost	35.3			(12.1		)	23.2
Net prior service credit arising during period	0.4			(0.1		)	0.3
Net deferred actuarial loss arising during period	(107.5		)	36.6			(70.9		)
Benefit plans, net	(70.7		)	24.0			(46.7		)
Currency translation adjustments	(11.6		)	—			(11.6		)
Loss from hedging activities	(3.2		)	1.1			(2.1		)
Other comprehensive loss attributable to W. R. Grace & Co. shareholders	$	(85.5	)	$	25.1		$	(60.4	)

Year Ended December 31, 2010 (In millions)	Pre-Tax Amount			Tax Benefit/ (Expense)			After-Tax Amount
Defined benefit pension and other postretirement plans:
Amortization of net prior service credit included in net periodic benefit cost	$	(2.9	)	$	1.0		$	(1.9	)
Amortization of net deferred actuarial loss included in net periodic benefit cost	35.8			(12.2		)	23.6
Net deferred actuarial loss arising during period	(55.2		)	18.7			(36.5		)
Benefit plans, net	(22.3		)	7.5			(14.8		)
Currency translation adjustments	12.2			—			12.2
Loss from hedging activities	(1.4		)	0.4			(1.0		)
Other comprehensive loss attributable to W. R. Grace & Co. shareholders	$	(11.5	)	$	7.9		$	(3.6	)

Schedule of components of accumulated other comprehensive loss

The following table presents the components of Grace's accumulated other comprehensive loss at December 31, 2012, 2011, and 2010:

Components of Accumulated Other Comprehensive Loss (In millions)	December 31,
	2012			2011			2010
Defined benefit pension and other postretirement plans:
Net prior service cost (net of tax)	$	(1.3	)	$	(1.8	)	$	(2.8	)
Net deferred actuarial loss (net of tax)	(640.5		)	(603.4		)	(555.7		)
Benefit plans, net	(641.8		)	(605.2		)	(558.5		)
Currency translation	35.6			30.2			41.8
Hedging activities, net of tax	(0.3		)	(2.7		)	(0.6		)
Unrealized loss on investment	(0.8		)	(0.8		)	(0.8		)
Accumulated other comprehensive loss	$	(607.3	)	$	(578.5	)	$	(518.1	)