Equity Investment - Schedule of Summarized Financial Information of Unaudited Financial Statements (Detail) - USD ($) $ in Thousands	3 Months Ended				12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Schedule of Equity Method Investments [Line Items]
Sales					$ 48,306	$ 40,457	$ 40,061
Net income	$ 49,058	$ 28,900	$ 37,241	$ 24,338	139,537	88,667	96,892
Current assets	242,543				242,543	91,396
Current liabilities	148,746				148,746	120,549
Ciner Wyoming
Schedule of Equity Method Investments [Line Items]
Sales					486,759	497,340	475,187
Gross profit					104,053	114,202	114,232
Net income					108,357	91,523	$ 91,596
Current assets	138,080				138,080	180,433
Noncurrent assets	252,743				252,743	228,002
Current liabilities	64,012				64,012	56,219
Noncurrent liabilities	$ 109,921				$ 109,921	$ 148,401