Employee Benefits (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
U.K. [Member]
Defined Benefit Plan Disclosure
Service cost	$ 0	$ 0	$ 0	$ 0
Interest cost	50	58	149	174
Expected return on plan assets	(77)	(82)	(229)	(247)
Amortization of net actuarial loss	11	13	31	40
Net periodic (benefit) cost	(16)	(11)	(49)	(33)
Curtailment loss (gain) and other	0	0	0	0
Total net periodic (benefit) cost	(16)	(11)	(49)	(33)
Estimate of contributions to defined benefit pension plans for the current fiscal year	65		65
Contributions made to defined benefit pension plans	16	24	50	145
U.S. [Member]
Defined Benefit Plan Disclosure
Service cost	0	0	2	0
Interest cost	33	32	99	96
Expected return on plan assets	(38)	(39)	(115)	(117)
Amortization of net actuarial loss	14	11	41	32
Net periodic (benefit) cost	9	4	27	11
Curtailment loss (gain) and other	0	0	(1)	1
Total net periodic (benefit) cost	9	4	26	12
Estimate of contributions to defined benefit pension plans for the current fiscal year	132		132
Contributions made to defined benefit pension plans	41	39	103	112
Other [Member]
Defined Benefit Plan Disclosure
Service cost	0	0	0	0
Interest cost	8	12	25	36
Expected return on plan assets	(12)	(15)	(37)	(45)
Amortization of net actuarial loss	2	2	8	6
Net periodic (benefit) cost	(2)	(1)	(4)	(3)
Curtailment loss (gain) and other	0	0	0	(3)
Total net periodic (benefit) cost	(2)	(1)	(4)	(6)
Estimate of contributions to defined benefit pension plans for the current fiscal year	23		23
Contributions made to defined benefit pension plans	$ 3	$ 7	$ 11	$ 23