Summary of Significant Accounting Policies - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2019 USD ($) Facility Customer Derivative Segment	Dec. 31, 2018 USD ($) Derivative	Dec. 31, 2017 USD ($)
Summary Of Significant Accounting Policies [Line Items]
Number of facilities for manufacture and distribution of products | Facility	4
Number of customers accounted as percentage of accounts receivable | Customer	9
Non-cash charge on long-lived assets written down	$ 9,701,000
Insurance coverage of general liability and auto liability risks	100,000,000
Insurance policy covering pollution liability	$ 50,000,000
Tax benefit recognized	Greater than 50%
Incentive tax credit receivable			$ 8,100,000
Number of derivatives held with fair value eligible for offset | Derivative	0	0
Number of reportable segment | Segment	1
Plant, Property and Equipment [Member]
Summary Of Significant Accounting Policies [Line Items]
Incentive tax credit receivable	$ 2,300,000	$ 3,100,000	7,400,000
Cost of Sales [Member]
Summary Of Significant Accounting Policies [Line Items]
Incentive tax credit receivable			$ 700,000
Non-core [Member]
Summary Of Significant Accounting Policies [Line Items]
Long-lived assets, held for sale		$ 0
Non-core [Member] | Other Expense [Member]
Summary Of Significant Accounting Policies [Line Items]
Non-cash charge on long-lived assets written down	$ 9,700,000
Receivables, Net [Member] | Customer Concentration Risk [Member]
Summary Of Significant Accounting Policies [Line Items]
Concentration risk, percentage	46.00%
Net Sales [Member] | Customer Concentration Risk [Member] | Koch Fertilizer LLC [Member]
Summary Of Significant Accounting Policies [Line Items]
Concentration risk, percentage	11.00%	13.00%	10.00%
Net Sales [Member] | Customer Concentration Risk [Member] | Coffeyville Resources Nitrogen Fertilizers L.L.C. [Member]
Summary Of Significant Accounting Policies [Line Items]
Concentration risk, percentage		11.00%
Net Sales [Member] | Customer Concentration Risk [Member] | Covestro [Member]
Summary Of Significant Accounting Policies [Line Items]
Concentration risk, percentage			12.00%
Minimum [Member]
Summary Of Significant Accounting Policies [Line Items]
Credit sales, payment terms	30 days
Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Credit sales, payment terms	60 days