Annual increase to contributions health care Cost.

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- Definition

The closing price (Level 1 measurement) on the date of contribution of the company's common stock that was contributed to the pension plans.

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Defined benefit plan contributions by employer in cash and common stock.

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Defined benefit plan contributions by employer in common stock.

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Defined contribution plan employee maximum contribution percentage.

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Defined contribution plan employee minimum contribution percentage.

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- Definition

Defined contribution plan guaranteed company match on employee contribution.

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Defined Contribution Plan, Number of Investment Options Offered

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- Definition

Discounted value shares valued for purposes of crediting the contribution to trust.

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Discount rate used to valued shares for purposes of crediting the contribution to the trust.

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- Definition

Employees earned a guaranteed company match on eligible compensation maximum.

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- Definition

Minimum funded percentage of accumulated benefit obligations for maintaining plan asset level.

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Rate at which shares valued for purposes of crediting the contribution to trust.

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Vested period company matching contributions for employee.

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- Definition

For defined benefit pension plans, the actuarial present value of benefits (whether vested or nonvested) attributed by the pension benefit formula to employee service rendered before a specified date and based on employee service and compensation (if applicable) before that date. The accumulated benefit obligation differs from the projected benefit obligation in that it includes no assumption about future compensation levels. For plans with flat-benefit or nonpay-related pension benefit formulas, the accumulated benefit obligation and the projected benefit obligation are the same.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Accumulated Benefit Obligation

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-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (e)

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- Definition

Amount of gain (loss) related to change in benefit obligation resulting from changes in actuarial assumptions, for example, but not limited to, interest, mortality, employee turnover, salary, and temporary deviation from the substantive plan.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 30

-Glossary Gain or Loss

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-Glossary Gain or Loss

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- Definition

The amount of the prior service cost or credit recognized in net periodic benefit cost relating to benefit changes attributable to plan participants' prior service pursuant to a plan amendment or a plan initiation.

+ References

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- Definition

The interest rate used to adjust for the time value of money for the plan.

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- Definition

An assumption as to the rate of return on plan assets reflecting the average rate of earnings expected on the funds invested or to be invested to provide for the benefits included in the benefit obligation.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 30

-Glossary Expected Long-Term Rate of Return on Plan Assets

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-Subparagraph (k)(3)

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- Definition

The increase in the fair value of plan assets from contributions made by the employer.

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- Definition

The amount of increase or decrease in the accumulated benefit obligation related to the effects of a change in the substantive terms of an existing defined benefit pension plan or the initiation of a new plan. A plan amendment may increase or decrease benefits, including those attributed to years of service already rendered.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 60

-Glossary Plan Amendment

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-Glossary Plan Amendment

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- Definition

Amount of benefits from a defined benefit plan expected to be paid in the next fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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- Definition

Amount included in accumulated other comprehensive income (AOCI) related to gain (loss) expected to be recognized as components of net periodic benefit cost for the fiscal year that follows the most recent annual statement of financial position.

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No definition available.

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- Definition

The assumed health care cost trend rate for the next year used to measure the expected cost of benefits covered by the plan (gross eligible charges). This is based upon the annual rate of change in the cost of health care benefits currently provided by the postretirement benefit plan, due to factors other than changes in the composition of the plan population by age and dependency status.

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-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

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-Paragraph 1

-Subparagraph (l)

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-Glossary Health Care Cost Trend Rate

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- Definition

The number of employer shares or related party shares included in plan assets.

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- Definition

Amount of net gain (loss) recognized in net periodic benefit cost as a result of an irrevocable action that relieves the employer (or the plan) of primary responsibility for a benefit obligation and eliminates significant risks related to the obligation and the assets used to effect the settlement. Examples of transactions that constitute a settlement include, but are not limited to, lump-sum cash payments to plan participants in exchange for their rights to receive specified benefits and purchasing nonparticipating annuity contracts to cover vested benefits.

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-Subparagraph (a)(1)

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- Definition

Amount of employer's best estimate of contributions expected to be paid to the plan during the next fiscal year beginning after the date of the latest statement of financial position.

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- Definition

The amount of decrease that relates to an irrevocable action that relieves the employer (or the plan) of primary responsibility for a benefit obligation and eliminates significant risks related to the obligation and the assets used to effect the settlement. Examples of transactions that constitute a settlement include (a) making lump-sum cash payments to plan participants in exchange for their rights to receive specified benefits and (b) purchasing nonparticipating annuity contracts.

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- Definition

The ultimate trend rate for health care costs.

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The amount of the cost recognized during the period for defined contribution plans.

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Employee Retirement Plans (Details Textual) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended			3 Months Ended
	Dec. 31, 2014 Investment_Option	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2013	Jun. 30, 2012	Dec. 31, 2011	Jun. 25, 2012
Defined Benefit Plan Disclosure [Line Items]
Reduction in measurement of APBO						$ 100
Accumulated benefit obligation	1,429	1,186		1,186
Minimum funded percentage of ABO	100.00%
Defined Contribution Plans Disclosure [Abstract]
Total charges for defined contribution plans	6	3	3
Minimum contribution percentage	1.00%
Maximum contribution percentage	75.00%
Number of investment options offered	22
Employees earned a guaranteed company on contributions	25.00%	10.00%	10.00%
Employees earned a guaranteed company match on eligible compensation, maximum	6.00%	6.00%	6.00%
Vested period company matching contributions for employee	3 years
Pension
Defined Benefit Plan Disclosure [Line Items]
Settlement charge	13	16	0
Actuarial loss	327	(115)
Weighted-average discount rate	4.10%	4.90%	4.20%	4.90%
Net actuarial loss	37
Prior service cost (credit)	0
Expected return on plan assets	7.00%	7.00%
Contribution by employer	64.0	71.0
Estimated contribution next fiscal year	67
Expected future benefit payments in next twelve months	86
USG Corporation Retirement Plan
Defined Benefit Plan Disclosure [Line Items]
Settlement charge		15
Reduction in measurement of PBO		80
Contributions by employer in common stock							1,249,219
Closing price per share of contributed shares							$ 16.48
Contribution by employer				20.6
Discounted value shares valued for purposes of crediting the contribution to trust							$ 16.01
Rate at which shares valued for purposes of crediting the contribution to trust							$ 16.48
Discount rate used to valued shares for purposes of crediting the contribution to the Trust							2.80%
Aggregate contribution by employer					20
Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Actuarial loss	4	(13)
Weighted-average discount rate	3.70%	4.60%		4.60%
Net actuarial loss	1
Prior service cost (credit)	(33)
Contribution by employer	12.0	13.0
Expected future benefit payments in next twelve months	$ 13
U.S. Postretirement Health Care Plan
Defined Benefit Plan Disclosure [Line Items]
Assumed health care cost trend rate	7.30%	8.00%
Ultimate health care cost trend rates	4.50%	5.00%
Annual increase to contributions health care cost	3.00%
Canadian Postretirement Health Care Plan
Defined Benefit Plan Disclosure [Line Items]
Assumed health care cost trend rate	8.25%	8.50%
Ultimate health care cost trend rates	4.00%	4.00%
Parent Common Stock \| Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Number of shares of common stock issued by employer	0