Employee Benefit Plans (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Domestic Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 8	$ 8
Interest cost	31	30
Expected return on plan assets	(40)	(42)
Net amortization	11	13
Net periodic benefit cost	10	9
Domestic Other Postretirement Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	3	4
Interest cost	8	7
Expected return on plan assets	(11)	(12)
Net amortization	(3)	(3)
Net periodic benefit cost	(3)	(4)
UK Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	5	6
Interest cost	19	20
Expected return on plan assets	(29)	(29)
Net amortization	12	16
Net periodic benefit cost	$ 7	$ 13