Retirement Benefits (Tables)

12 Months Ended

Dec. 31, 2011

Defined Benefit Plan Disclosure [Line Items]

Schedule of estimated future benefit payaments for its pension and postretirement benefits

December 31,	Pension Benefits				Postretirement Benefits
(In millions of dollars)	U.S.		Non-U.S.		U.S.		Non-U.S.
2012	$	197	$	247	$	11	$	4
2013	$	207	$	253	$	12	$	4
2014	$	218	$	267	$	12	$	4
2015	$	230	$	283	$	12	$	4
2016	$	242	$	301	$	12	$	4
2017-2021	$	1,395	$	1,786	$	61	$	25

Summary of the U.S. and non-U.S. plans investments measured at fair value on a recurring basis

	Fair Value Measurements at December 31, 2011
Assets (In millions of dollars)	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total
Common/Collective trusts	$	10	$	4,837	$	—	$	4,847
Corporate obligations	—		1,792		1		1,793
Corporate stocks	1,716		15		8		1,739
Private equity/Partnerships	—		1		779		780
Government securities	10		368		—		378
Real estate	14		4		319		337
Short-term investment funds	288		42		—		330
Company common stock	253		—		—		253
Other investments	1		34		202		237
Insurance group annuity contracts	—		—		20		20
Swaps	—		5		—		5
Total investments	$	2,292	$	7,098	$	1,329	$	10,719

	Fair Value Measurements at December 31, 2010
Assets (In millions of dollars)	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total
Common/Collective trusts	$	—	$	4,471	$	—	$	4,471
Corporate obligations	—		1,103		8		1,111
Corporate stocks	1,939		1		1		1,941
Private equity/Partnerships	—		1		746		747
Government securities	—		547		—		547
Real estate	3		5		293		301
Short-term investment funds	561		49		—		610
Company common stock	219		—		—		219
Other investments	3		8		177		188
Insurance group annuity contracts	—		—		20		20
Swaps	—		9		—		9
Total investments	$	2,725	$	6,194	$	1,245	$	10,164

Summary of changes in the fair value of the plans' Level 3 assets

Assets (In millions)	Fair Value, January 1, 2011		Purchases		Sales			Unrealized Gain/ (Loss)			Realized Gain/ (Loss)			Exchange Rate Impact			Transfers in/(out) and Other			Fair Value, December 31, 2011
Private equity/Partnerships	$	746	$	119	$	(80	)	$	(83	)	$	70		$	7		$	—		$	779
Real estate	293		—		—			22			(1		)	5			—			319
Other investments	177		32		(13		)	6			2			(2		)	—			202
Insurance group annuity contracts	20		151		(150		)	8			(9		)	—			—			20
Corporate stocks	1		8		—			(1		)	—			—			—			8
Corporate obligations	8		1		(8		)	2			(1		)	—			(1		)	1
Total assets	$	1,245	$	311	$	(251	)	$	(46	)	$	61		$	10		$	(1	)	$	1,329

Assets (In millions)	Fair Value, January 1, 2010		Purchases		Sales			Unrealized Gain/ (Loss)			Realized Gain/ (Loss)			Exchange Rate Impact			Transfers in/(out) and Other			Fair Value, December 31, 2010
Private equity/Partnerships	$	637	$	138	$	(54	)	$	15		$	22		$	(12	)	$	—		$	746
Real estate	269		—		—			34			—			(10		)	—			293
Other investments	180		19		(16		)	3			1			(14		)	4			177
Insurance group annuity contracts	17		141		(140		)	2			—			—			—			20
Corporate stocks	11		1		(4		)	(3		)	1			—			(5		)	1
Corporate obligations	5		2		(2		)	3			(1		)	—			1			8
Government securities	3		—		(3		)	—			—			—			—			—
Total assets	$	1,122	$	301	$	(219	)	$	54		$	23		$	(36	)	$	—		$	1,245

Combined US & Significant Non-US Plans [Member]

Defined Benefit Plan Disclosure [Line Items]

Schedule of weighted average actuarial assumptions utilized defined benefit plans

	Pension Benefits				Postretirement Benefits
	2011		2010		2011		2010
Weighted average assumptions:
Discount rate (for expense)	5.59	%	6.00	%	5.81	%	6.27	%
Expected return on plan assets	8.19	%	8.18	%	—	%	—	%
Rate of compensation increase (for expense)	4.08	%	4.16	%	—	%	—	%
Discount rate (for benefit obligation)	4.91	%	5.59	%	5.05	%	5.84	%
Rate of compensation increase (for benefit obligation)	3.09	%	4.09	%	—	%	—	%

Schedule of components of net periodic benefit cost for U.S. defined benefit and other postretirement benefit plans

Combined U.S. and significant non-U.S. Plans	Pension									Postretirement
For the Years Ended December 31,	Benefits									Benefits
(In millions of dollars)	2011			2010			2009			2011			2010			2009
Service cost	$	226		$	197		$	188		$	5		$	4		$	5
Interest cost	609			578			551			13			14			17
Expected return on plan assets	(887		)	(815		)	(788		)	—			—			—
Amortization of prior service credit	(19		)	(21		)	(49		)	(13		)	(13		)	(13		)
Recognized actuarial loss (credit)	215			144			70			(4		)	—			1
Net periodic benefit cost	$	144		$	83		$	(28	)	$	1		$	5		$	10

U.S. Plans [Member]

Defined Benefit Plan Disclosure [Line Items]

Schedule of weighted average actuarial assumptions utilized defined benefit plans

	U.S. Pension Benefits				U.S.  Postretirement Benefits
	2011		2010		2011		2010
Weighted average assumptions:
Discount rate (for expense)	5.90	%	6.35	%	5.95	%	6.30	%
Expected return on plan assets	8.75	%	8.75	%	—		—
Rate of compensation increase (for expense)	3.90	%	3.90	%	—		—
Discount rate (for benefit obligation)	5.15	%	5.90	%	5.10	%	6.00	%
Rate of compensation increase (for benefit obligation)	2.00	%	3.90	%	—		—

Schedule of components of net periodic benefit cost for U.S. defined benefit and other postretirement benefit plans

U.S. Plans only	Pension									Postretirement
For the Years Ended December 31,	Benefits									Benefits
(In millions of dollars)	2011			2010			2009			2011			2010			2009
Service cost	$	83		$	76		$	76		$	3		$	3		$	4
Interest cost	231			227			219			8			10			12
Expected return on plan assets	(315		)	(295		)	(293		)	—			—			—
Amortization of prior service credit	(16		)	(18		)	(47		)	(13		)	(13		)	(13		)
Recognized actuarial loss (credit)	100			71			52			(4		)	—			1
Net periodic benefit cost (credit)	$	83		$	61		$	7		$	(6	)	$	—		$	4

Schedule of MMC's defined benefit plans and postretirement plans

December 31,	U.S. Pension Benefits						U.S.  Postretirement Benefits
(In millions of dollars)	2011			2010			2011			2010
Change in benefit obligation:
Benefit obligation at beginning of year	$	4,041		$	3,629		$	180		$	163
Service cost	83			76			3			3
Interest cost	231			227			8			10
Actuarial (gain) loss	352			270			(20		)	12
Medicare Part D subsidy	—			—			4			3
Benefits paid	(174		)	(161		)	(13		)	(11		)
Benefit obligation at end of year	$	4,533		$	4,041		$	162		$	180
Change in plan assets:
Fair value of plan assets at beginning of year	$	3,444		$	2,959		$	—		$	—
Actual return on plan assets	199			425			—			—
Employer contributions	24			221			9			8
Medicare Part D subsidy	—			—			4			3
Benefits paid	(174		)	(161		)	(13		)	(11		)
Fair value of plan assets at end of year	$	3,493		$	3,444		$	—		$	—
Funded status	$	(1,040	)	$	(597	)	$	(162	)	$	(180	)
Net liability recognized	$	(1,040	)	$	(597	)	$	(162	)	$	(180	)
Amounts recognized in the consolidated balance sheets:
Current liabilities	$	(124	)	$	(23	)	$	(9	)	$	(11	)
Noncurrent liabilities	(916		)	(574		)	(153		)	(169		)
	$	(1,040	)	$	(597	)	$	(162	)	$	(180	)
Amounts not yet recognized in net periodic cost and included in accumulated other comprehensive income:
Unrecognized prior service credit	$	39		$	55		$	13		$	26
Unrecognized net actuarial (loss) gain	(1,695		)	(1,327		)	12			(4		)
Total amounts included in accumulated other comprehensive income	$	(1,656	)	$	(1,272	)	$	25		$	22
Cumulative employer contributions in excess of net periodic cost	616			675			(187		)	(202		)
Net amount recognized in consolidated balance sheet	$	(1,040	)	$	(597	)	$	(162	)	$	(180	)
Accumulated benefit obligation at December 31	$	4,467		$	3,929		$	—		$	—

December 31,	U.S. Pension Benefits						U.S.  Postretirement Benefits
(In millions of dollars)	2011			2010			2011			2010
Reconciliation of unrecognized prior service credit:
Amount disclosed as of prior year-end	$	55		$	73		$	26		$	39
Recognized as component of net periodic benefit credit	(16		)	(18		)	(13		)	(13		)
Amount at end of year	$	39		$	55		$	13		$	26

Schedule of unrecognized net actuarial gain (loss)

December 31,	U.S. Pension Benefits						U.S.  Postretirement Benefits
(In millions of dollars)	2011			2010			2011			2010
Reconciliation of unrecognized prior service credit:
Amount disclosed as of prior year-end	$	55		$	73		$	26		$	39
Recognized as component of net periodic benefit credit	(16		)	(18		)	(13		)	(13		)
Amount at end of year	$	39		$	55		$	13		$	26

Schedule of total recognized in net periodic benefit cost and other comprehensive income (loss)

December 31,	U.S. Pension Benefits						U.S.  Postretirement Benefits
(In millions of dollars)	2011			2010			2011			2010
Reconciliation of unrecognized net actuarial gain (loss):
Amount disclosed as of prior year-end	$	(1,327	)	$	(1,258	)	$	(4	)	$	9
Recognized as component of net periodic benefit cost	100			71			(4		)	—
Changes in plan assets and benefit obligations recognized in other comprehensive income:
Liability experience	(352		)	(269		)	20			(13		)
Asset experience	(116		)	129			—			—
Total gain (loss) recognized as change in plan assets and benefit obligations	(468		)	(140		)	20			(13		)
Amount at end of year	$	(1,695	)	$	(1,327	)	$	12		$	(4	)

For the Years Ended December 31,	U.S. Pension Benefits						U.S. Postretirement Benefits
(In millions of dollars)	2011		2010		2009		2011			2010		2009
Total recognized in net periodic benefit cost and other comprehensive loss (income)	$	467	$	148	$	42	$	(9	)	$	26	$	(7	)

Schedule of change in assumed health care cost trend rates

(In millions of dollars)	1 Percentage Point Increase		1 Percentage Point Decrease
Effect on total of service and interest cost components	$	—	$	(1	)
Effect on postretirement benefit obligation	$	1	$	(16	)

Schedule of estimated amounts that will be amortized from accumulated other comprehensive in the next fiscal year

	U.S. Pension Benefits			U.S. Postretirement Benefits
(In millions of dollars)	2012			2012
Prior service credit	$	(16	)	$	(12	)
Net actuarial loss (gain)	146			(1		)
Projected cost (credit)	$	130		$	(13	)

Non-U.S. Plans [Member]

Defined Benefit Plan Disclosure [Line Items]

Schedule of weighted average actuarial assumptions utilized defined benefit plans

December 31,	Non-U.S. Pension Benefits				Non-U.S. Postretirement Benefits
(In millions of dollars)	2011		2010		2011		2010
Weighted average assumptions:
Discount rate (for expense)	5.41	%	5.80	%	5.51	%	6.20	%
Expected return on plan assets	7.91	%	7.90	%	—	%	—	%
Rate of compensation increase (for expense)	4.19	%	4.30	%	—	%	—	%
Discount rate (for benefit obligation)	4.77	%	5.40	%	4.95	%	5.50	%
Rate of compensation increase (for benefit obligation)	3.73	%	4.20	%	—	%	—	%

Schedule of components of net periodic benefit cost for U.S. defined benefit and other postretirement benefit plans

For the Years Ended December 31,	Non-U.S. Pension Benefits									Non-U.S. Postretirement Benefits
(In millions of dollars)	2011			2010			2009			2011		2010		2009
Service cost	$	143		$	121		$	112		$	2	$	1	$	1
Interest cost	378			351			332			5		4		5
Expected return on plan assets	(572		)	(520		)	(495		)	—		—		—
Amortization of prior service cost	(3		)	(3		)	(2		)	—		—		—
Recognized actuarial loss	115			73			18			—		—		—
Net periodic benefit cost (credit)	61			22			(35		)	7		5		6
Settlement (credit)/loss	—			5			1			—		—		—
Curtailment (credit)/loss	—			—			—			—		—		—
Special termination benefits	—			1			—			—		—		—
Total cost (credit)	$	61		$	28		$	(34	)	$	7	$	5	$	6

Schedule of unrecognized net actuarial gain (loss)

December 31,	Non-U.S. Pension Benefits						Non-U.S. Postretirement Benefits
(In millions of dollars)	2011			2010			2011		2010
Reconciliation of prior service credit (cost):
Amount disclosed as of prior year-end	$	23		$	24		$	1	$	1
Recognized as component of net periodic benefit credit	3			(2		)	—		—
Changes in plan assets and benefit obligations recognized in other comprehensive income:
Plan amendments	(3		)	—			—		—
Exchange rate adjustments	—			1			—		—
Amount at end of year	$	23		$	23		$	1	$	1

Schedule of defined benefit plans disclosures and unrecognized net actuarial gain (loss) [Table Text Block]

December 31,	Non-U.S. Pension Benefits						Non-U.S. Postretirement Benefits
(In millions of dollars)	2011			2010			2011			2010
Change in benefit obligation:
Benefit obligation at beginning of year	$	6,802		$	6,354		$	83		$	70
Service cost	143			121			2			1
Interest cost	378			351			5			4
Employee contributions	14			16			—			—
Actuarial loss	575			430			5			11
Plan amendments	(3		)	—			—			—
Effect of settlement	(7		)	(17		)	—			—
Effect of curtailment	(1		)	(2		)	—			—
Special termination benefits	—			1			—			—
Benefits paid	(266		)	(244		)	(4		)	(3		)
Foreign currency changes	66			(208		)	—			—
Newly disclosed plans	16			—			—			—
Benefit obligation at end of year	$	7,717		$	6,802		$	91		$	83
Change in plan assets:
Fair value of plan assets at beginning of year	$	6,741		$	6,183		$	—		$	—
Actual return on plan assets	311			765			—			—
Effect of settlement	(6		)	(17		)	—			—
Company contributions	320			237			4			3
Employee contributions	14			16			—			—
Benefits paid	(266		)	(244		)	(4		)	(3		)
Foreign currency changes	82			(202		)	—			—
Newly disclosed plans	12			—			—			—
Other	(2		)	3			—			—
Fair value of plan assets at end of year	$	7,206		$	6,741		$	—		$	—
Funded status	$	(511	)	$	(61	)	$	(91	)	$	(83	)
Net liability recognized	$	(511	)	$	(61	)	$	(91	)	$	(83	)
Amounts recognized in the consolidated balance sheets:
Non-current assets	$	39		$	265		$	—		$	—
Current liabilities	(106		)	(8		)	(4		)	(4		)
Non-current liabilities	(444		)	(318		)	(87		)	(79		)
	$	(511	)	$	(61	)	$	(91	)	$	(83	)
Amounts not yet recognized in net periodic cost and included in accumulated other comprehensive income:
Unrecognized prior service credit	$	23		$	23		$	1		$	1
Unrecognized net actuarial loss	(3,038		)	(2,305		)	(19		)	(14		)
Total amounts included in AOCI	$	(3,015	)	$	(2,282	)	$	(18	)	$	(13	)
Cumulative employer contributions in excess of net periodic cost	2,504			2,221			(73		)	(70		)
Net amount recognized in consolidated balance sheet	$	(511	)	$	(61	)	$	(91	)	$	(83	)
Accumulated benefit obligation at December 31	$	7,246		$	6,313		$	—		$	—

December 31,	Non-U.S. Pension Benefits						Non-U.S. Postretirement Benefits
(In millions of dollars)	2011			2010			2011		2010
Reconciliation of prior service credit (cost):
Amount disclosed as of prior year-end	$	23		$	24		$	1	$	1
Recognized as component of net periodic benefit credit	3			(2		)	—		—
Changes in plan assets and benefit obligations recognized in other comprehensive income:
Plan amendments	(3		)	—			—		—
Exchange rate adjustments	—			1			—		—
Amount at end of year	$	23		$	23		$	1	$	1

December 31,	Non-U.S.  Pension Benefits						Non-U.S. Postretirement Benefits
(In millions of dollars)	2011			2010			2011			2010
Reconciliation of net actuarial loss:
Amount disclosed as of prior year-end	$	(2,305	)	$	(2,268	)	$	(14	)	$	(4	)
Recognized as component of net periodic benefit cost	115			73			—			—
Effect of settlement	—			5			—			—
Changes in plan assets and benefit obligations recognized in other comprehensive income:
Liability experience	(575		)	(430		)	(5		)	(10		)
Asset experience	(261		)	244			—			—
Effect of curtailment	(1		)	2			—			—
Total amount recognized as change in plan assets and benefit obligations	(837		)	(184		)	(5		)	(10		)
Exchange rate adjustments	(11		)	69			—			—
Amount at end of year	$	(3,038	)	$	(2,305	)	$	(19	)	$	(14	)

For the Years Ended December 31,	Non-U.S. Pension Benefits						Non-U.S. Postretirement Benefits
(In millions of dollars)	2011		2010		2009		2011		2010		2009
Total recognized in net periodic benefit cost and other comprehensive loss	$	792	$	66	$	519	$	12	$	15	$	3

Schedule of total recognized in net periodic benefit cost and other comprehensive income (loss)

December 31,	Non-U.S.  Pension Benefits						Non-U.S. Postretirement Benefits
(In millions of dollars)	2011			2010			2011			2010
Reconciliation of net actuarial loss:
Amount disclosed as of prior year-end	$	(2,305	)	$	(2,268	)	$	(14	)	$	(4	)
Recognized as component of net periodic benefit cost	115			73			—			—
Effect of settlement	—			5			—			—
Changes in plan assets and benefit obligations recognized in other comprehensive income:
Liability experience	(575		)	(430		)	(5		)	(10		)
Asset experience	(261		)	244			—			—
Effect of curtailment	(1		)	2			—			—
Total amount recognized as change in plan assets and benefit obligations	(837		)	(184		)	(5		)	(10		)
Exchange rate adjustments	(11		)	69			—			—
Amount at end of year	$	(3,038	)	$	(2,305	)	$	(19	)	$	(14	)

For the Years Ended December 31,	Non-U.S. Pension Benefits						Non-U.S. Postretirement Benefits
(In millions of dollars)	2011		2010		2009		2011		2010		2009
Total recognized in net periodic benefit cost and other comprehensive loss	$	792	$	66	$	519	$	12	$	15	$	3

Schedule of change in assumed health care cost trend rates

(In millions of dollars)	1 Percentage Point Increase		1 Percentage Point Decrease
Effect on total of service and interest cost components	$	1	$	—
Effect on postretirement benefit obligation	$	10	$	(8	)

Schedule of estimated amounts that will be amortized from accumulated other comprehensive in the next fiscal year

	Non-U.S. Pension Benefits			Non-U.S. Postretirement Benefits
(In millions of dollars)	2012			2012
Prior service credit	$	3		$	—
Net actuarial loss	(116		)	(1		)
Projected cost	$	(113	)	$	(1	)