Income Taxes - Additional Information (Details) - USD ($)	3 Months Ended	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax [Line Items]
U.S. corporate income tax rate			35.00%	35.00%	35.00%
Provisional net credit	$ 273,000,000		$ 272,900,000	$ 0	$ 0
Valuation allowance	11,200,000		11,200,000	8,000,000
Deferred tax assets, valuation allowances	23,500,000		23,500,000	20,200,000
Repatriation of foreign cash					93,000,000
Income taxes			(50,700,000)	246,900,000	225,000,000
Deferred tax benefit			2,500,000	(2,400,000)	(9,800,000)
One-time repatriation tax on deemed earnings of foreign subsidiaries			10,000,000
Undistributed earnings of foreign subsidiaries	0		0
Uncertain tax positions or unrecognized tax benefits	0		0	0	0	$ 4,000,000
Foreign Cash Repatriated
Income Tax [Line Items]
Income taxes					2,700,000
Deferred tax benefit					11,600,000
Natronx Technologies LLC
Income Tax [Line Items]
Deferred tax assets, valuation allowances				7,700,000	$ 7,700,000
Quimica Geral Do Nordeste Sa
Income Tax [Line Items]
Deferred tax assets, valuation allowances	2,400,000		2,400,000	$ 4,500,000
Foreign Tax Authority
Income Tax [Line Items]
Loss carryforward	36,500,000		36,500,000
Loss carryforward subject to expiration	500,000		$ 500,000
Loss carryforward expiration date			Dec. 31, 2022
Foreign Tax Authority | Unrealized Foreign Tax Credit Carryforwards
Income Tax [Line Items]
Deferred tax assets, valuation allowances	$ 9,900,000		$ 9,900,000
Scenario, Forecast
Income Tax [Line Items]
U.S. corporate income tax rate		21.00%