Employee Retirement Plans (Tables)

12 Months Ended

Dec. 31, 2017

Retirement Benefits [Abstract]

Schedule of Net Benefit Costs

The location of the settlement expense within our consolidated statements of income and the group of employees for which it is related is as follows:

(millions)		2017		2016
Cost of products sold	USG retirees or terminated vested employees	$	10	$	7
Selling and administrative expenses	USG retirees or terminated vested employees	2		4
(Loss) income from discontinued operations	Terminated employees of L&W	13		—
Gain on sale of discontinued operations	Terminated employees of L&W	—		15
Total		$	25	$	26

Summary of components of net pension and postretirement benefits costs

The components of net pension and postretirement benefit costs are summarized in the following table:

(millions)	2017			2016			2015
Pension Benefits:
Service cost of benefits earned	$	44		$	45		$	49
Interest cost on projected benefit obligation	61			66			66
Expected return on plan assets	(93		)	(89		)	(83		)
Settlement (a)	25			35			1
Net amortization	22			22			39
Net pension cost (b)	$	59		$	79		$	72
Postretirement Benefits:
Service cost of benefits earned	$	2		$	2		$	2
Interest cost on projected benefit obligation	5			6			6
Curtailment	—			(20		)	—
Net amortization	(23		)	(27		)	(31		)
Net postretirement benefit (c)	$	(16	)	$	(39	)	$	(23	)

(a) In 2016, $26 million of the settlement charge reflects the increase in lump sum benefits paid largely driven by the sale of L&W and $9 million reflected payments from our supplemental plan.

(b) Net pension costs, excluding settlement costs, includes amounts allocated to (loss) income from discontinued operations for L&W totaling a benefit of $1 million for 2017 and expense of $7 million for 2016 and $12 million for 2015.

(c) Net postretirement benefit, excluding curtailment gain, includes a net benefit allocated to (loss) income from discontinued operations for L&W of $1 million for 2017, $3 million for 2016 and $3 million for 2015.

Schedule of accumulated benefit obligation for the defined benefit pension plans

	As of December 31,
(millions)	2017			2016
Selected information for pension plans with accumulated benefit obligations in excess of plan assets:
Accumulated benefit obligation	$	(35	)	$	(39	)
Fair value of plan assets	3			2
Selected information for pension plans with benefit obligations in excess of plan assets:
Benefit obligation	$	(1,769	)	$	(1,384	)
Fair value of plan assets	1,576			1,205

Summary of projected benefit obligations, plan assets and funded status

The following table summarizes projected benefit obligations, plan assets and funded status as of December 31:

	Pension						Postretirement
(millions)	2017			2016			2017			2016
Change in Benefit Obligation:
Benefit obligation as of January 1	$	1,610		$	1,564		$	135		$	144
Service cost	44			45			2			2
Interest cost	61			66			5			6
Settlements	(121		)	(123		)	—			—
Curtailments	—			(37		)	—			(7		)
Participant contributions	9			11			—			—
Benefits paid	(51		)	(33		)	(6		)	(7		)
Actuarial (gain) loss	202			112			10			(5		)
Foreign currency translation	16			5			4			2
Benefit obligation as of December 31	$	1,770		$	1,610		$	150		$	135
Change in Plan Assets:
Fair value as of January 1	$	1,435		$	1,301		$	—		$	—
Actual return on plan assets	217			107			—			—
Employer contributions	71			167			6			7
Participant contributions	9			11			—			—
Benefits paid	(51		)	(33		)	(6		)	(7		)
Settlements	(121		)	(123		)	—			—
Foreign currency translation	17			5			—			—
Fair value as of December 31	$	1,577		$	1,435		$	—		$	—
Funded status	$	(193	)	$	(175	)	$	(150	)	$	(135	)
Components on the Consolidated Balance Sheets:
Noncurrent assets	$	—		$	4		$	—		$	—
Current liabilities	(8		)	(16		)	(9		)	(8		)
Noncurrent liabilities	(185		)	(163		)	(141		)	(127		)
Net liability as of December 31	$	(193	)	$	(175	)	$	(150	)	$	(135	)
Pretax Components in AOCI:
Net actuarial loss	$	421		$	388		$	11		$	—
Prior service credit	—			(1		)	(42		)	(65		)
Total as of December 31	$	421		$	387		$	(31	)	$	(65	)

Schedule of assumptions used in the accounting for the plans

The following tables reflect the assumptions used in the accounting for our plans:

	Pension				Postretirement
	2017		2016		2017		2016
Weighted average assumptions used to determine benefit obligations as of December 31:
Discount rate	3.55	%	4.02	%	3.42	%	3.90	%
Compensation increase rate	3.54	%	3.55	%	N/A		N/A
Weighted average assumptions used to determine net cost for years ended December 31:
Discount rate	4.02	%	4.43	%	3.90	%	4.24	%
Expected return on plan assets	6.54	%	6.66	%	N/A		N/A
Compensation increase rate	3.55	%	3.55	%	N/A		N/A

Schedule of effect of one percentage point change in the assumed health care cost trend rates

A one percentage point change in the assumed health care cost trend rates would have the following effects on our Canadian plans:

(millions)	One-Percentage- Point Increase		One-Percentage- Point Decrease
Effect on total service and interest cost	$	1	$	—
Effect on postretirement benefit obligation	13		(10		)

Schedule of aggregate target asset allocation on a weighted average basis for all the plans and the acceptable ranges around the targets

The following table shows the aggregate target asset allocation on a weighted average basis for all the plans and the acceptable ranges around the targets as of December 31, 2017.

		Investment Policy
Asset Categories	Asset Category Description	Target	Range
Equity	Institutional commingled/pooled equity funds, equity mutual funds and direct holdings of the common stock of U.S. and non-U.S. companies; equity funds and direct holdings are invested in companies with a range of market capitalizations	36%	32%-40%
Fixed income	U.S. Treasury securities, non-U.S. government debt securities such as Canadian federal bonds, corporate bonds of companies from diversified industries and mortgage-backed securities	54%	45%-63%
Limited partnerships	Investments in funds that follow any of several different strategies, including investing in distressed debt, energy development, infrastructure, and hedge funds. These investments use strategies with returns normally expected to have a reduced correlation to the return of equities as compared to other asset classes and often provide a current income component that is a meaningful portion of the investment’s total return.	5%	1%-8%
Other real assets	Primarily investments in large core, private real estate funds that directly own a diverse portfolio of properties located in the United States. It also includes an allocation to funds investing in equities of real estate and infrastructure companies	5%	2%-9%
Cash equivalents and short-term investments	Primarily held in short-term investment funds or registered money market funds with daily liquidity	—%	0%-5%
Total		100%

Schedule of fair values by hierarchy of inputs

The fair values by hierarchy of inputs as of December 31 were as follows:

	Quoted Prices in Active Markets for Identical Assets (Level 1)				Significant Other Observable Inputs (Level 2)				Significant Unobservable Inputs (Level 3)				Total
(millions)	2017		2016		2017		2016		2017		2016		2017			2016
Asset Categories:
Equity:
Common and preferred stock	$	92	$	66	$	—	$	—	$	—	$	—	$	92		$	66
Commingled/pooled/mutual funds (a)	—		—		553		490		—		—		553			490
Total equity	92		66		553		490		—		—		645			556
Fixed income:
U.S. government and agency debt securities	—		—		8		194		—		—		8			194
Non-U.S. government and agency debt securities	—		—		68		54		—		—		68			54
Investment-grade debt securities	—		—		334		197		—		—		334			197
High-yield debt securities	—		—		42		53		—		—		42			53
Commingled/pooled funds (a)	—		—		305		165		—		—		305			165
Mortgaged backed securities	—		—		1		3		—		—		1			3
Other	—		—		13		10		1		1		14			11
Total fixed income	—		—		771		676		1		1		772			677
Limited partnerships	—		—		—		—		91		103		91			103
Other real estate assets	—		—		18		16		39		38		57			54
Cash equivalents and short-term investments	—		—		14		11		—		—		14			11
Total	$	92	$	66	$	1,356	$	1,193	$	131	$	142	$	1,579		$	1,401
Cash on hand													—			—
Receivables													2			35
Accounts payable													(4		)	(1		)
Total													$	1,577		$	1,435

(a) Certain investments in commingled/pooled equity funds have been classified as Level 2 because observable quoted prices for these institutional funds are not available.

Reconciliation of the change in the fair value measurement of the defined benefit plans’ consolidated assets

A reconciliation of the change in the fair value measurement of the defined benefit plans’ consolidated assets using significant unobservable inputs (Level 3) between January 1, 2016 and December 31, 2017 is as follows:

(millions)	Fixed Income		Other Real Estate Assets			Limited Partnerships			Total
Balance as of January 1, 2016	$	1	$	37		$	106		$	144
Realized losses	—		1			5			6
Unrealized gains	—		2			(3		)	(1		)
Purchases, sales and settlements:
Purchases	—		—			1			1
Sales	—		(2		)	(6		)	(8		)
Settlements	—		—			—			—
Net transfers into (out of) Level 3	—		—			—			—
Balance as of December 31, 2016	$	1	$	38		$	103		$	142
Realized gains	—		1			15			16
Unrealized gains (losses)	—		2			(1		)	1
Purchases, sales and settlements:
Purchases	—		—			9			9
Sales	—		(2		)	(35		)	(37		)
Settlements	—		—			—			—
Net transfers into (out of) Level 3	—		—			—			—
Balance as of December 31, 2017	$	1	$	39		$	91		$	131

Schedule of expected benefit payments

Total benefit payments we expect to make to participants, which include payments funded from USG’s assets as well as payments from our pension plans' assets, are as follows (in millions):

Years ended December 31	Pension Benefits		Postretirement Benefits
2018	$	120	$	9
2019	125		9
2020	137		8
2021	134		8
2022	141		8
2023 - 2027	634		42