Employee Benefits (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
U.K. [Member]
Defined Benefit Plan Disclosure
Service cost	$ 0	$ 0	$ 0	$ 0
Interest cost	50	58	99	116
Expected return on plan assets	(77)	(83)	(152)	(165)
Amortization of net actuarial loss	10	14	20	27
Net periodic (benefit) cost	(17)	(11)	(33)	(22)
Curtailment loss (gain) and other	0	0	0	0
Total net periodic (benefit) cost	(17)	(11)	(33)	(22)
Estimate of contributions to defined benefit pension plans for the current fiscal year	65		65
Contributions made to defined benefit pension plans	15	56	34	121
U.S. [Member]
Defined Benefit Plan Disclosure
Service cost	1	0	2	0
Interest cost	33	32	66	64
Expected return on plan assets	(38)	(39)	(77)	(78)
Amortization of net actuarial loss	13	11	27	21
Net periodic (benefit) cost	9	4	18	7
Curtailment loss (gain) and other	0	0	(1)	1
Total net periodic (benefit) cost	9	4	17	8
Estimate of contributions to defined benefit pension plans for the current fiscal year	132		132
Contributions made to defined benefit pension plans	28	33	62	73
Other [Member]
Defined Benefit Plan Disclosure
Service cost	0	0	0	0
Interest cost	9	12	17	24
Expected return on plan assets	(13)	(15)	(25)	(30)
Amortization of net actuarial loss	3	2	6	4
Net periodic (benefit) cost	(1)	(1)	(2)	(2)
Curtailment loss (gain) and other	0	0	0	(3)
Total net periodic (benefit) cost	(1)	(1)	(2)	(5)
Estimate of contributions to defined benefit pension plans for the current fiscal year	23		23
Contributions made to defined benefit pension plans	$ 4	$ 4	$ 8	$ 16