Retirement Plans (Tables)

12 Months Ended

Dec. 31, 2017

Compensation And Retirement Disclosure [Abstract]

Change in Benefit Obligation, Fair Value of Plan Assets, and Funded Status of Pension Plans and Postretirement Medical Plan

The following table summarizes the benefit obligations, the fair value of plan assets, and the funded status of our pension and postretirement medical plans:

	Funded						Unfunded						Postretirement
	Pension Plans						Pension Plan						Medical Plan
	2017			2016			2017			2016			2017			2016
	(In millions)
Change In Benefit Obligation
Balance at January 1	$	2,560		$	2,321		$	256		$	259		$	84		$	98
Service cost		36			44			13			16			4			4
Interest cost		93			98			9			9			3			3
Actuarial loss (gain) (a)		138			162			10			(5	)		3			(13	)
Benefit payments (b)		(113	)		(132	)		(39	)		(23	)		(7	)		(8	)
Plan curtailments		(3	)		(2	)		—			—			—			—
Special termination benefits		—			1			—			—			—			—
Assumption of HOVENSA pension plan		—			151			—			—			—			—
Foreign currency exchange rate changes		54			(83	)		—			—			—			—
Balance at December 31		2,765			2,560			249			256			87			84
Change In Fair Value of Plan Assets
Balance at January 1	$	2,284		$	2,206		$	—		$	—		$	—		$	—
Actual return on plan assets		351			153			—			—			—			—
Employer contributions		158			26			39			23			7			8
Benefit payments (b)		(113	)		(132	)		(39	)		(23	)		(7	)		(8	)
Assumption of HOVENSA pension plan		—			126			—			—			—			—
Foreign currency exchange rate changes		52			(95	)		—			—			—			—
Balance at December 31		2,732			2,284			—			—			—			—
Funded Status (Plan assets greater (less) than benefit obligations) at December 31	$	(33	)	$	(276	)	$	(249	)	$	(256	)	$	(87	)	$	(84	)
Unrecognized Net Actuarial (Gains) Losses	$	789		$	895		$	84		$	93		$	(10	)	$	(13	)

(a) The change in discount rate in 2017 resulted in total actuarial losses of approximately $170 million (2016: $175 million).

(b) Benefit payments include lump-sum settlement payments of $57 million in 2017 (2016: $65 million).

Pension Plans and Postretirement Medical Plan Amounts Recognized in Consolidated Balance Sheet

  Amounts recognized in the Consolidated Balance Sheet at December 31 consisted of the following:

	Funded						Unfunded						Postretirement
	Pension Plans						Pension Plan						Medical Plan
	2017			2016			2017			2016			2017			2016
	(In millions)
Pension asset / (accrued benefit liability)	$	(33	)	$	(276	)	$	(249	)	$	(256	)	$	(87	)	$	(84	)
Accumulated other comprehensive loss, pre-tax (a)		789			895			84			93			(10	)		(13	)

(a) The after‑tax deficit reflected in Accumulated other comprehensive income (loss) was $548 million at December 31, 2017 (2016: $660 million deficit).

Components of Net Periodic Benefit Cost for Funded and Unfunded Pension Plans and Postretirement Medical Plan

The net periodic benefit cost for funded and unfunded pension plans, and the postretirement medical plan, is as follows:

	Pension Plans									Postretirement Medical Plan
	2017			2016			2015			2017		2016		2015
	(In millions)
Service cost	$	49		$	60		$	67		$	4	$	4	$	4
Interest cost		102			107			102			3		3		3
Expected return on plan assets		(168	)		(166	)		(168	)		—		—		—
Amortization of unrecognized net actuarial losses		58			60			75			—		—		—
Settlement loss		19			—			17			—		—		—
Special termination benefit recognized		—			1			1			—		—		—
Net Periodic Benefit Cost	$	60		$	62		$	94		$	7	$	7	$	7

Actuarial Assumptions Used For Pension Plans & Postretirement Medical Plan

The weighted average actuarial assumptions used for funded and unfunded pension plans were as follows:

	2017			2016			2015
Weighted Average Assumptions Used to Determine Benefit Obligations at December 31
Discount rate		3.3	%		3.7	%		4.1	%
Rate of compensation increase		4.5	%		4.6	%		4.5	%
Weighted Average Assumptions Used to Determine Net Periodic Benefit Cost for the Years Ended December 31
Discount rate		3.7	%		4.1	%		3.8	%
Expected return on plan assets		7.3	%		7.4	%		7.5	%
Rate of compensation increase		4.6	%		4.5	%		5.0	%

The actuarial assumptions used for postretirement medical plan, as follows:

	2017			2016			2015
Assumptions Used to Determine Benefit Obligations at December 31
Discount rate		3.2	%		3.5	%		3.5	%
Initial health care trend rate		7.3	%		7.7	%		6.7	%
Ultimate trend rate		4.5	%		4.5	%		4.5	%
Year in which ultimate trend rate is reached		2038			2038			2038

Fair Value of Financial Assets of Funded Pension Plans

The following tables provide the fair value of the financial assets of the funded pension plans as of December 31, 2017 and 2016 in accordance with the fair value measurement hierarchy described in Note 1, Nature of Operations, Basis of Presentation and Summary of Accounting Policies.

	Level 1		Level 2		Level 3		Total
	(In millions)
December 31, 2017
Cash and Short-Term Investment Funds	$	32	$	69	$	—	$	101
Equities:
U.S. equities (domestic)		789		—		—		789
International equities (non-U.S.)		104		330		—		434
Global equities (domestic and non-U.S.)		2		238		—		240
Fixed Income:
Treasury and government issued (a)		—		271		—		271
Government related (b)		—		34		1		35
Mortgage-backed securities (c)		—		166		—		166
Corporate		—		188		—		188
Other:
Hedge funds		—		—		187		187
Private equity funds		—		—		140		140
Real estate funds		63		—		94		157
Diversified commodities funds		—		24		—		24
	$	990	$	1,320	$	422	$	2,732
December 31, 2016
Cash and Short-Term Investment Funds	$	9	$	79	$	—	$	88
Equities:
U.S. equities (domestic)		550		—		—		550
International equities (non-U.S.)		160		275		—		435
Global equities (domestic and non-U.S.)		2		197		—		199
Fixed Income:
Treasury and government issued (a)		—		202		—		202
Government related (b)		—		38		—		38
Mortgage-backed securities (c)		—		164		2		166
Corporate		1		186		—		187
Other:
Hedge funds		—		—		209		209
Private equity funds		—		—		126		126
Real estate funds		10		—		52		62
Diversified commodities funds		—		22		—		22
	$	732	$	1,163	$	389	$	2,284

(a) Includes securities issued and guaranteed by U.S. and non‑U.S. governments.

(b) Primarily consists of securities issued by governmental agencies and municipalities.

(c) Comprised of U.S. residential and commercial mortgage-backed securities.

Changes in Financial Assets that are Measured at Fair Value Based on Level 3 Inputs that are held by Institutional Funds

The following tables provide changes in financial assets that are measured at fair value based on Level 3 inputs that are held by institutional funds classified as:

							Private			Real
	Fixed			Hedge			Equity			Estate
	Income			Funds			Funds			Funds			Total
	(In millions)
Balance at January 1, 2016	$	3		$	216		$	122		$	52		$	393
Actual return on plan assets		—			(7	)		5			7			5
Purchases, sales or other settlements		(1	)		—			(1	)		(7	)		(9	)
Net transfers in (out) of Level 3		—			—			—			—			—
Balance at December 31, 2016		2			209			126			52			389
Actual return on plan assets		—			3			18			11			32
Purchases, sales or other settlements		—			(25	)		(4	)		31			2
Net transfers in (out) of Level 3		(1	)		—			—			—			(1	)
Balance at December 31, 2017	$	1		$	187		$	140		$	94		$	422

Estimated Future Benefit Payments for Funded and Unfunded Pension Plans and Postretirement Medical Plan

Estimated future benefit payments by the funded and unfunded pension plans, and the postretirement medical plan, which reflect expected future service, are as follows (in millions):

2018	$	127
2019		142
2020		142
2021		141
2022		145
Years 2023 to 2027		748