Employee Benefits (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
U.S. Pension Plan
Defined Benefit Plan Disclosure
Interest cost	$ 30	$ 30
Expected return on plan assets	(32)	(30)
Amortization of net actuarial loss	11	8
Net periodic benefit cost	9	8
Estimate of contributions to defined benefit pension plans for the current fiscal year	237
Contributions made to defined benefit pension plans	18
International Pension Plan
Defined Benefit Plan Disclosure
Service cost	4	5
Interest cost	66	66
Expected return on plan assets	(80)	(71)
Amortization of net actuarial loss	14	13
Net periodic benefit cost	4	13
Estimate of contributions to defined benefit pension plans for the current fiscal year	304
Contributions made to defined benefit pension plans	$ 105