Debt - Long-term Debt (Details) - USD ($)	Sep. 30, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Long-term debt	$ 400,429,000	$ 443,035,000
Less - Current maturities of long-term debt	(57,476,000)	(42,473,000)
Less - Unamortized debt issuance costs	(7,716,000)	(9,935,000)
Long term debt	335,237,000	390,627,000
Finance Leases And Other Debt
Debt Instrument [Line Items]
Long-term debt	10,429,000	805,000
Secured Debt \| Term Loan Facility
Debt Instrument [Line Items]
Long-term debt	380,000,000	400,000,000
Secured Debt \| Revolving Credit Facility
Debt Instrument [Line Items]
Long-term debt	0	20,000,000
Secured Debt \| Credit Facility
Debt Instrument [Line Items]
Long-term debt	380,000,000	420,000,000
Notes Payable, Other Payables \| Plateau Excavation
Debt Instrument [Line Items]
Long-term debt	10,000,000	10,000,000
Tealstone Construction \| Notes Payable, Other Payables
Debt Instrument [Line Items]
Long-term debt	$ 0	$ 12,230,000

Long-term Debt, Current Maturities, Gross

No definition available.

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- Definition

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (b)(1)
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-SubTopic 210
-Section S99
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-Section S99
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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.

+ References

No definition available.

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- Definition

Amount, after accumulated amortization, of debt issuance costs classified as current. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
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-SubTopic 30
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- Definition

Amount after unamortized (discount) premium and debt issuance costs of long-term debt classified as noncurrent and excluding amounts to be repaid within one year or the normal operating cycle, if longer. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

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