Related-Party Transactions - Additional Information (Details)	1 Months Ended		3 Months Ended		12 Months Ended
	Jan. 31, 2019 USD ($) land	Apr. 30, 2015 USD ($) Facility $ / T	Mar. 31, 2019 USD ($) Renewal Lease Trust $ / T shares	Mar. 31, 2018 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Related Party Transaction [Line Items]
Financing receivables - affiliate			$ 3,459,000			$ 3,392,000
Reimbursement partnership			$ 1,900,000	$ 2,500,000
Class of Warrant or Right, Outstanding | shares			50,480
Term Loan due 2022
Related Party Transaction [Line Items]
Long-term debt			$ 762,906,000			$ 762,906,000
Transport and Overriding Royalty Agreements
Related Party Transaction [Line Items]
Total remaining minimum payments of transportation lease			76,200,000
Unearned income from financing leasing services			24,100,000
Outstanding financing receivable			52,100,000
Financing receivables - affiliate			$ 3,200,000
New River Royalty, LLC
Related Party Transaction [Line Items]
Operating lease number of leases | Lease			2
Lease expiration date			Oct. 15, 2021
Lease renewal terms			5 years
Rental fee			$ 100,000
Number of tracts of land purchased | land	2
Payments to acquire land	$ 6,100,000
Reserves Investor Group
Related Party Transaction [Line Items]
Number of trusts established | Trust			4
Murray Energy And Affiliated Entities
Related Party Transaction [Line Items]
General partner ownership interest			80.00%
Subordinated limited partner ownership interest, description			owner of all of the outstanding subordinated limited partner units
Limited partners ownership interest			12.00%
Reimbursement partnership				200,000
Murray Energy And Affiliated Entities | Transportation Arrangements
Related Party Transaction [Line Items]
Loadout services			$ 0	$ 0
Manager
Related Party Transaction [Line Items]
Management and administration services, quarterly payment			5,200,000
Manager | Predecessor
Related Party Transaction [Line Items]
Management and administration services, quarterly payment		$ 3,500,000
Management and administration services, annual payment		14,000,000
Manager | Scenario, Forecast
Related Party Transaction [Line Items]
Management and administration services, quarterly payment					$ 5,000,000
Management and administration services, annual payment					$ 20,000,000
American Energy Corporation | Transport and Overriding Royalty Agreements
Related Party Transaction [Line Items]
Proceeds from sale of equipment		$ 63,000,000
Number of coal preparation plants and related cost handling facilities | Facility		2
American Energy Corporation | Transport and Overriding Royalty Agreements | Minimum
Related Party Transaction [Line Items]
Fees per ton of coal mined processed and/or transported using leased assets | $ / T		1.15
Quarterly minimum Fees for coal mined processed and/or transported using leased assets		$ 1,700,000
American Energy Corporation | Transport and Overriding Royalty Agreements | Maximum
Related Party Transaction [Line Items]
Fees per ton of coal mined processed and/or transported using leased assets | $ / T		1.75
American Energy and Consolidated Land Company | Transport and Overriding Royalty Agreements
Related Party Transaction [Line Items]
Cash paid for overriding royalty rights		$ 12,000,000
American Energy and Consolidated Land Company | Transport and Overriding Royalty Agreements | Minimum
Related Party Transaction [Line Items]
Overriding royalty interest granted per unit | $ / T		0.30
Cash paid for overriding royalty rights		$ 500,000
American Energy and Consolidated Land Company | Transport and Overriding Royalty Agreements | Maximum
Related Party Transaction [Line Items]
Overriding royalty interest granted per unit | $ / T		0.50
American Energy and Consolidated Land Company | ORRA
Related Party Transaction [Line Items]
Outstanding financing receivable			11,300,000
Financing receivables - affiliate			200,000
Remaining minimum payments under agreement			27,700,000
Unearned income under agreement			$ 16,400,000
Colt LLC
Related Party Transaction [Line Items]
Lease term			10 years
Number of renewals | Renewal			6
Lessor renewal term			5 years
Lease payment per ton | $ / T			3.40
Percentage of gross price			8.00%
Ruger LLC
Related Party Transaction [Line Items]
Lease term			10 years
Number of renewals | Renewal			6
Lessor renewal term			5 years
Lease payment per ton | $ / T			3.40
Percentage of gross price			8.00%
Ruger LLC | Royalties
Related Party Transaction [Line Items]
Percentage of gross price			8.00%
Sitran Terminal | New River Royalty, LLC
Related Party Transaction [Line Items]
Lease expiration date			Dec. 31, 2020
Lease renewal terms			5 years
Rental fee			$ 50,000
Cline Resource and Development Company ("CRDC") | Reserves Investor Group | Term Loan due 2022
Related Party Transaction [Line Items]
Long-term debt			9,900,000
Cline Resource and Development Company ("CRDC") | Reserves Investor Group | Second Lien Notes due 2023
Related Party Transaction [Line Items]
Long-term debt			$ 25,000,000
Cline Trust Company LLC | Reserves Investor Group
Related Party Transaction [Line Items]
Class of Warrant or Right, Outstanding | shares			17,556
Cline Trust Company LLC | Reserves Investor Group | Term Loan due 2022
Related Party Transaction [Line Items]
Long-term debt			$ 9,900,000