Retirement Benefits (Narrative) (Details) employee in Thousands		1 Months Ended	12 Months Ended
	Dec. 03, 2014 USD ($)	Sep. 30, 2014 employee	Dec. 31, 2016 USD ($) amendment subsidy	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2013	Jan. 01, 2007 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Number of retirees receiving pension payments from annuity | employee		30
Transfer of plan assets	$ 3,200,000,000
Settlement of pension plan			$ 26,000,000	$ 0	$ 1,917,000,000
Additional eligible compensation after IRS limit							$ 175,000
Curtailment gain			$ 0	32,000,000	0
Period of market-related asset value method of recognizing assets related gains and losses			5 years
Deferred compensation plan, employer percentage of matching			4.00%
Deferred compensation plan, maximum employer contribution for board officers			$ 50,000
Defined contribution plan, expenses for material defined contribution plans			26,000,000	28,000,000	31,000,000
Defined contribution plan, discretionary matching contributions made during period			$ 0	0	0
Minimum
Defined Benefit Plan Disclosure [Line Items]
Amortization period of prior service cost			1 year
Period range of amortizing gains and losses recognized			11 years
Maximum
Defined Benefit Plan Disclosure [Line Items]
Amortization period of prior service cost			8 years
Period range of amortizing gains and losses recognized			34 years
Regular Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Lump sum distribution to participants expense					1,000,000,000
U.S. Pension Benefit Plans
Defined Benefit Plan Disclosure [Line Items]
Years of service required			1 year
Settlement of pension plan			$ 0	0	1,883,000,000
Curtailment gain			0	0	0
Amortization of unrecognized net loss and prior service cost for next fiscal year			44,000,000
Interest cost			(182,000,000)	(193,000,000)	(370,000,000)
Service cost			0	0	0
Company contributions			3,000,000	3,000,000
Net periodic pension cost			(1,000,000)	27,000,000	1,969,000,000
Actuarial present value of the future death benefits			4,644,000,000	4,304,000,000	4,536,000,000
Postretirement Health Care Benefits Plan
Defined Benefit Plan Disclosure [Line Items]
Settlement of pension plan			$ 0	0	0
Retirement age when retirees are provided an annual subsidiary to use toward the purchase of health care			65 years			65 years
Number of plan amendments | amendment			2
Number of fixed rate subsidies | subsidy			1
Maximum annual participant subsidy			$ 560
Amortization period of prior service cost			5 years
Curtailment gain			$ 0	0	0
Amortization of unrecognized net loss and prior service cost for next fiscal year			13,000,000
Interest cost			(4,000,000)	(8,000,000)	(10,000,000)
Service cost			0	(1,000,000)	(2,000,000)
Company contributions			0	0
Net periodic pension cost			(27,000,000)	(51,000,000)	(39,000,000)
Actuarial present value of the future death benefits			83,000,000	192,000,000	212,000,000
Non U.S. Pension Benefit Plans
Defined Benefit Plan Disclosure [Line Items]
Settlement of pension plan			26,000,000	0	0
Curtailment gain			0	32,000,000	0
Amortization of unrecognized net loss and prior service cost for next fiscal year			15,000,000
Interest cost			(55,000,000)	(66,000,000)	(80,000,000)
Service cost			(11,000,000)	(12,000,000)	(15,000,000)
Company contributions			8,000,000	10,000,000
Net periodic pension cost			10,000,000	(43,000,000)	10,000,000
Actuarial present value of the future death benefits			1,791,000,000	1,815,000,000	2,075,000,000
Postretirement Health Coverage
Defined Benefit Plan Disclosure [Line Items]
Company contributions			0	0
Split-dollar Life Insurance Arrangement
Defined Benefit Plan Disclosure [Line Items]
Net periodic pension cost			5,000,000	5,000,000	$ 5,000,000
Actuarial present value of the future death benefits			58,000,000	$ 63,000,000
Change in Accounting Method Accounted for as Change in Estimate [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost			28,000,000
Service cost			0
Change in Accounting Method Accounted for as Change in Estimate [Member] | U.S. Pension Benefit Plans
Defined Benefit Plan Disclosure [Line Items]
Interest cost			18,000,000
Change in Accounting Method Accounted for as Change in Estimate [Member] | Postretirement Health Care Benefits Plan
Defined Benefit Plan Disclosure [Line Items]
Interest cost			4,000,000
Change in Accounting Method Accounted for as Change in Estimate [Member] | Non U.S. Pension Benefit Plans
Defined Benefit Plan Disclosure [Line Items]
Interest cost			$ 6,000,000