Employee Benefits (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
U.S. Pension Plan
Defined Benefit Plan Disclosure
Service cost	$ 0	$ 0
Interest cost	28	30
Expected return on plan assets	(34)	(32)
Amortization of net actuarial loss	13	11
Net periodic benefit cost	7	9
Estimate of contributions to defined benefit pension plans for the current fiscal year	167
Contributions made to defined benefit pension plans	33
International Pension Plan
Defined Benefit Plan Disclosure
Service cost	5	4
Interest cost	64	66
Expected return on plan assets	(90)	(80)
Amortization of net actuarial loss	18	14
Net periodic benefit cost	(3)	4
Estimate of contributions to defined benefit pension plans for the current fiscal year	381
Contributions made to defined benefit pension plans	$ 167