Postretirement Benefit Plans (Tables)

3 Months Ended

Mar. 31, 2012

Defined Benefit Pension Plans and Defined Benefit Postretirement Plans Disclosure [Abstract]

Effect on operations of the pension plans

	Principal Pension Plans				Other Pension Plans
	Three months ended March 31				Three months ended March 31
(In millions)	2012		2011		2012		2011
Service cost for benefits earned	$	348	$	278	$	85	$	68
Prior service cost amortization		70		46		1		4
Expected return on plan assets		(945)		(984)		(155)		(148)
Interest cost on benefit obligation		616		663		127		126
Net actuarial loss amortization		846		572		69		34
Pension plans cost	$	935	$	575	$	127	$	84

Effect on operations of principal retiree health and life insurance plans

	Principal Retiree Health
	and Life Insurance Plans
	Three months ended March 31
(In millions)	2012		2011
Service cost for benefits earned	$	56	$	47
Prior service cost amortization		151		160
Expected return on plan assets		(19)		(24)
Interest cost on benefit obligation		129		151
Net actuarial gain amortization		0		(29)
Retiree benefit plans cost	$	317	$	305