SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)

12 Months Ended

Dec. 31, 2017

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

Summary of intangible assets

	December 31, 2017						December 31, 2016
			Accumulated		Intangibles,				Accumulated		Intangibles,
	Original Cost		Amortization		Net		Original Cost		Amortization		Net
	(in thousands)
Non-compete agreements	$	9,697	$	(7,378)	$	2,319	$	14,542	$	(10,974)	$	3,568
Customer contracts and other, net		48,970		(36,462)		12,508		54,978		(33,300)		21,678
Mining permits		1,500		(178)		1,322		1,500		(104)		1,396
Total	$	60,167	$	(44,018)	$	16,149	$	71,020	$	(44,378)	$	26,642

Schedule of amortization expense attributable to intangible assets

Year Ended December 31,		(in thousands)
2018	$	6,918
2019		7,737
2020		391
2021		74
2022		74
Thereafter		955

Summary of advance royalties

	2017		2016
	(in thousands)
Advance royalties, affiliates (see Note 18 – Related-Party Transactions)	$	32,993	$	19,820
Advance royalties, third-parties		11,177		10,759
Total advance royalties, net	$	44,170	$	30,579