Segment Reporting - Sales and Segment Contribution Margin for Reporting Segments and Other Operating Results (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Segment Reporting Information
Total sales	$ 427,433	$ 290,465	$ 796,746	$ 535,262
Selling, general and administrative	(42,232)	(25,839)	(76,823)	(47,978)
Depreciation, depletion and amortization	(36,563)	(23,626)	(65,155)	(45,225)
Asset impairment	(16,184)	0	(16,184)	0
Interest expense	(20,214)	(8,105)	(27,284)	(15,751)
Other income (expense), net, including interest income	1,081	638	1,746	(4,779)
Income tax expense	(2,832)	(7,110)	(10,353)	(5,396)
Net income	17,644	29,459	48,938	31,981
Operating Segments
Segment Reporting Information
Total sales	427,433	290,465	796,746	535,262
Total segment contribution margin	155,908	94,489	275,872	153,546
Segment Reconciling Items
Segment Reporting Information
Operating activities excluded from segment cost of sales	(21,320)	(988)	(32,881)	(2,436)
Selling, general and administrative	(42,232)	(25,839)	(76,823)	(47,978)
Depreciation, depletion and amortization	(36,563)	(23,626)	(65,155)	(45,225)
Asset impairment	(16,184)	0	(16,184)	0
Interest expense	(20,214)	(8,105)	(27,284)	(15,751)
Other income (expense), net, including interest income	1,081	638	1,746	(4,779)
Oil & Gas Proppants
Segment Reporting Information
Total sales	324,063		636,993
Oil & Gas Proppants | Operating Segments
Segment Reporting Information
Total sales	324,063	235,018	636,993	427,976
Total segment contribution margin	114,607	71,222	214,041	110,062
Industrial & Specialty Products
Segment Reporting Information
Total sales	103,370		159,753
Industrial & Specialty Products | Operating Segments
Segment Reporting Information
Total sales	103,370	55,447	159,753	107,286
Total segment contribution margin	$ 41,301	$ 23,267	$ 61,831	$ 43,484