Pension Plans, Retirement Benefits and Savings Plans (details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Pension Plans [Member]
Change in projected benefit obligation [Roll Forward]
Benefit obligation, balance, beginning of year	$ 3,612	$ 3,117
Benefits earned	131	110	$ 118
Interest cost on benefit obligation	144	150	132
Actuarial loss (gain)	(201)	457
Benefits paid	(199)	(198)
Plan amendments		(8)
Curtailment		(3)
Settlement		(6)
Foreign currency exchange rate change, change in projected benefit obligation	(9)	(7)
Benefit obligation, balance, end of year	3,478	3,612	3,117
Change in plan assets [Roll Forward]
Fair value of plan assets, balance, beginning of year	3,357	3,203
Actual return on plan assets	(14)	159
Company contributions	107	207
Benefits paid	(199)	(198)
Foreign currency exchange rate change, change in plan assets	(9)	(8)
Settlement		(6)
Fair value of plan assets, balance, end of year	3,242	3,357	3,203
Funded status of plan at end of year	(236)	(255)
Amounts recognized in the consolidated balance sheet consist of:
Accrued over-funded benefit plan assets	4	6
Accrued under-funded benefit plan liabilities	(240)	(261)
Total amount recognized in the consolidated balance sheet	(236)	(255)
Amounts recognized in accumulated other comprehensive income consist of:
Net actuarial loss	1,131	1,185
Prior service benefit	(8)	(8)
Total amount recognized in accumulated other comprehensive income	1,123	1,177
Qualified Domestic Pension Plan [Member]
Change in projected benefit obligation [Roll Forward]
Benefit obligation, balance, beginning of year	3,385	2,908
Benefits earned	124	104
Interest cost on benefit obligation	135	140
Actuarial loss (gain)	(203)	428
Benefits paid	(191)	(187)
Plan amendments		(8)
Benefit obligation, balance, end of year	3,250	3,385	2,908
Change in plan assets [Roll Forward]
Fair value of plan assets, balance, beginning of year	3,235	3,074
Actual return on plan assets	(17)	148
Company contributions	100	200	0
Benefits paid	(191)	(187)
Fair value of plan assets, balance, end of year	3,127	3,235	3,074
Funded status of plan at end of year	(123)	(150)
Amounts recognized in the consolidated balance sheet consist of:
Accrued under-funded benefit plan liabilities	(123)	(150)
Total amount recognized in the consolidated balance sheet	(123)	(150)
Amounts recognized in accumulated other comprehensive income consist of:
Net actuarial loss	1,079	1,132
Prior service benefit	(8)	(8)
Total amount recognized in accumulated other comprehensive income	1,071	1,124
Nonqualified and Foreign Pension Plans [Member]
Change in projected benefit obligation [Roll Forward]
Benefit obligation, balance, beginning of year	227	209
Benefits earned	7	6
Interest cost on benefit obligation	9	10
Actuarial loss (gain)	2	29
Benefits paid	(8)	(11)
Curtailment		(3)
Settlement		(6)
Foreign currency exchange rate change, change in projected benefit obligation	(9)	(7)
Benefit obligation, balance, end of year	228	227	209
Change in plan assets [Roll Forward]
Fair value of plan assets, balance, beginning of year	122	129
Actual return on plan assets	3	11
Company contributions	7	7
Benefits paid	(8)	(11)
Foreign currency exchange rate change, change in plan assets	(9)	(8)
Settlement		(6)
Fair value of plan assets, balance, end of year	115	122	129
Funded status of plan at end of year	(113)	(105)
Amounts recognized in the consolidated balance sheet consist of:
Accrued over-funded benefit plan assets	4	6
Accrued under-funded benefit plan liabilities	(117)	(111)
Total amount recognized in the consolidated balance sheet	(113)	(105)
Amounts recognized in accumulated other comprehensive income consist of:
Net actuarial loss	52	53
Total amount recognized in accumulated other comprehensive income	52	53
Postretirement Benefit Plans [Member]
Change in projected benefit obligation [Roll Forward]
Benefit obligation, balance, beginning of year	255	211
Interest cost on benefit obligation	10	10	9
Actuarial loss (gain)	(3)	51
Benefits paid	(13)	(15)
Plan amendments	(11)
Foreign currency exchange rate change, change in projected benefit obligation	(5)	(2)
Benefit obligation, balance, end of year	233	255	211
Change in plan assets [Roll Forward]
Fair value of plan assets, balance, beginning of year	16	17
Company contributions	12	14
Benefits paid	(13)	(15)
Fair value of plan assets, balance, end of year	15	16	$ 17
Funded status of plan at end of year	(218)	(239)
Amounts recognized in the consolidated balance sheet consist of:
Accrued under-funded benefit plan liabilities	(218)	(239)
Total amount recognized in the consolidated balance sheet	(218)	(239)
Amounts recognized in accumulated other comprehensive income consist of:
Net actuarial loss	4	9
Prior service benefit	(35)	(26)
Total amount recognized in accumulated other comprehensive income	$ (31)	$ (17)