Long-Lived Assets (Narrative) (Details) $ in Thousands	1 Months Ended	12 Months Ended
Dec. 31, 2019 USD ($)	Dec. 31, 2019 USD ($)
Impairment Effects on Earnings Per Share [Line Items]
Asset impairment		$ 77,882
Carlisle Assets [Member]
Impairment Effects on Earnings Per Share [Line Items]
Mine carrying value	$ 1,800	1,800
Asset impairment		65,700
Cost to close mine	3,000	3,000
Equipment redeployed		23,000
Hourglass Sands LLC [Member]
Impairment Effects on Earnings Per Share [Line Items]
Mine carrying value	1,900	1,900
Asset impairment	$ 2,900	$ 9,200

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Undiscounted amount of the accrual for environmental loss contingencies expected to be paid in the remainder of the 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.

+ References

No definition available.

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- Definition

Amount of write-down of assets recognized in the income statement. Includes, but is not limited to, losses from tangible assets, intangible assets and goodwill.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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- Definition

Mineral properties, net of adjustments.

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