Employment Benefit Plans (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 10	$ 12
Interest cost	24	22
Expected return on plan assets	(34)	(31)
Amortization of net loss	0	4
Net cost recognized	0	7
Other Postretirement Benefit Plans, Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Interest cost	3	3
Amortization of prior service credits	(1)	0
Amortization of net loss	1	1
Net cost recognized	$ 3	$ 4