Discontinued Operations - Summary of Financial Results of Discontinued Operations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 0	$ 2,847	$ 1,200	$ 11,529
Accounts receivable, net	993	23,967
Inventory		7,553
Prepaid expenses and other		2,056
Total current assets of discontinued operations	993	36,423
Noncurrent assets
Land		1,239
Plant and equipment, net		44,822
Mineral rights, net		105,466
Intangible assets, net		2,734
Other assets		1,681
Total assets of discontinued operations	993	192,365
Current liabilities:
Accounts payable (including affiliates)	181	6,019
Accrued liabilities	766	5,348
Other		401
Total current liabilities of discontinued operations	947	11,768
Noncurrent liabilities
Other non-current liabilities		2,220
Total liabilities of discontinued operations	947	13,988
Discontinued Operations, Held-for-sale [Member]
Revenues and other income:
Construction aggregates	116,066	112,970	103,755
Road construction and asphalt paving services	18,400	18,411	17,047
Oil and gas	(3)	38	16,486
Gain on asset sales, net	13,414	22	8,287
Total revenues and other income	147,877	131,441	145,575
Operating expenses
Operating and maintenance expenses (including affiliates)	117,702	111,923	112,159
Depreciation, depletion and amortization	12,218	12,579	22,033
Asset impairments	232	64	1,629
Total operating expenses	130,152	124,566	135,821
Interest expense, net	38	693	3,488
Income (loss) from discontinued operations	17,687	6,182	6,266
Disposal Group, Including Discontinued Operation, Additional Disclosures [Abstract]
Cash paid for interest	0	0	1,906
Plant, equipment and mineral rights funded with accounts payable or accrued liabilities	881	294	0
NRP Oil and Gas [Domain]
Current assets:
Cash and cash equivalents		0
Accounts receivable, net	988	991
Inventory		0
Prepaid expenses and other		0
Total current assets of discontinued operations		991
Noncurrent assets
Land		0
Plant and equipment, net		0
Mineral rights, net		0
Intangible assets, net		0
Other assets		0
Total assets of discontinued operations	988	991
Current liabilities:
Accounts payable (including affiliates)	0	0
Accrued liabilities	0	0
Other		401
Total current liabilities of discontinued operations		401
Noncurrent liabilities
Other non-current liabilities		0
Total liabilities of discontinued operations	0	401
Construction Aggregates
Current assets:
Cash and cash equivalents		2,847
Accounts receivable, net	5	22,976
Inventory		7,553
Prepaid expenses and other		2,056
Total current assets of discontinued operations		35,432
Noncurrent assets
Land		1,239
Plant and equipment, net		44,822
Mineral rights, net		105,466
Intangible assets, net		2,734
Other assets		1,681
Total assets of discontinued operations	5	191,374
Current liabilities:
Accounts payable (including affiliates)	181	6,019
Accrued liabilities	766	5,348
Other		0
Total current liabilities of discontinued operations		11,367
Noncurrent liabilities
Other non-current liabilities		2,220
Total liabilities of discontinued operations	947	13,587
NRP Oil and Gas [Domain] | Discontinued Operations, Held-for-sale [Member]
Revenues and other income:
Construction aggregates	0	0	0
Road construction and asphalt paving services	0	0	0
Oil and gas	(3)	38	16,486
Gain on asset sales, net	0	(289)	8,274
Total revenues and other income	(3)	(251)	24,760
Operating expenses
Operating and maintenance expenses (including affiliates)	134	290	11,503
Depreciation, depletion and amortization	0	0	7,527
Asset impairments	0	0	564
Total operating expenses	134	290	19,594
Interest expense, net		0	3,488
Income (loss) from discontinued operations	(137)	(541)	1,678
Construction Aggregates | Discontinued Operations, Held-for-sale [Member]
Revenues and other income:
Construction aggregates	116,066	112,970	103,755
Road construction and asphalt paving services	18,400	18,411	17,047
Oil and gas	0	0	0
Gain on asset sales, net	13,414	311	13
Total revenues and other income	147,880	131,692	120,815
Operating expenses
Operating and maintenance expenses (including affiliates)	117,568	111,633	100,656
Depreciation, depletion and amortization	12,218	12,579	14,506
Asset impairments	232	64	1,065
Total operating expenses	130,018	124,276	116,227
Interest expense, net	38	693	0
Income (loss) from discontinued operations	$ 17,824	$ 6,723	$ 4,588