Employee Benefits (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
U.K. [Member]
Defined Benefit Plan Disclosure
Service cost	$ 0	$ 0
Interest cost	58	53
Expected return on plan assets	(82)	(75)
Amortization of net actuarial loss	13	12
Net periodic (benefit) cost	(11)	(10)
Curtailment loss (gain) and other	0	0
Net periodic (benefit) cost	(11)	(10)
Estimate of contributions to defined benefit pension plans for the current fiscal year	185
Contributions made to defined benefit pension plans	65
U.S. [Member]
Defined Benefit Plan Disclosure
Service cost	0	0
Interest cost	32	28
Expected return on plan assets	(39)	(34)
Amortization of net actuarial loss	10	13
Net periodic (benefit) cost	3	7
Curtailment loss (gain) and other	1	0
Net periodic (benefit) cost	4	7
Estimate of contributions to defined benefit pension plans for the current fiscal year	173
Contributions made to defined benefit pension plans	40
Other [Member]
Defined Benefit Plan Disclosure
Service cost	0	5
Interest cost	12	11
Expected return on plan assets	(15)	(15)
Amortization of net actuarial loss	2	6
Net periodic (benefit) cost	(1)	7
Curtailment loss (gain) and other	(3)	0
Net periodic (benefit) cost	(4)	7
Estimate of contributions to defined benefit pension plans for the current fiscal year	27
Contributions made to defined benefit pension plans	$ 12