Employee Benefits Schedule of changes in Level 3 fair value for U.K. Pension Plans (Details) (U.K. [Member], USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013		Dec. 31, 2012
Change in fair value of plan assets
Balance at the beginning of the period	$ 4,860		$ 4,245
Actual return on plan assets:
Foreign exchange	104		146
Balance at the end of the period	5,398		4,860
Significant Unobservable Inputs (Level 3) [Member]
Change in fair value of plan assets
Balance at the beginning of the period	1,084		851
Actual return on plan assets:
Relating to assets still held at the end of the year	20		16
Relating to assets sold during the year	8		12
Purchases, sales and settlements—net	1		173
Transfer in/(out) of Level 3	0		0
Foreign exchange	20		32
Balance at the end of the period	1,133		1,084
Significant Unobservable Inputs (Level 3) [Member] | Global [Member]
Actual return on plan assets:
Balance at the end of the period	0	[1]	0	[1]
Significant Unobservable Inputs (Level 3) [Member] | Annuities [Member]
Change in fair value of plan assets
Balance at the beginning of the period	568		419
Actual return on plan assets:
Relating to assets still held at the end of the year	(13)		(4)
Relating to assets sold during the year	0		0
Purchases, sales and settlements—net	0		137
Transfer in/(out) of Level 3	0		0
Foreign exchange	9		16
Balance at the end of the period	564		568
Significant Unobservable Inputs (Level 3) [Member] | Pooled funds - Real estate [Member]
Change in fair value of plan assets
Balance at the beginning of the period	70	[1],[2]	97
Actual return on plan assets:
Relating to assets still held at the end of the year	1		1
Relating to assets sold during the year	3		1
Purchases, sales and settlements—net	(50)		(32)
Transfer in/(out) of Level 3	0		0
Foreign exchange	(1)		3
Balance at the end of the period	23	[1],[2]	70	[1],[2]
Significant Unobservable Inputs (Level 3) [Member] | Alternative investments [Member]
Change in fair value of plan assets
Balance at the beginning of the period	446	[1],[3]	335
Actual return on plan assets:
Relating to assets still held at the end of the year	32		19
Relating to assets sold during the year	5		11
Purchases, sales and settlements—net	51		68
Transfer in/(out) of Level 3	0		0
Foreign exchange	12		13
Balance at the end of the period	$ 546	[1],[3]	$ 446	[1],[3]

[1] Consists of various equity, fixed income, commodity, and real estate mutual fund type investment vehicles.

[2] Consists of property funds and trusts holding direct real estate investments.

[3] Consists of limited partnerships, private equity and hedge funds.