Contingencies and Other Information - Narrative (Details) $ in Thousands	3 Months Ended			24 Months Ended
	Jun. 30, 2019 USD ($) facility	Sep. 30, 2018	Mar. 31, 2013 USD ($)	Dec. 31, 2005 USD ($)	Mar. 18, 2014 USD ($)	Oct. 26, 2007 USD ($)
Loss Contingencies [Line Items]
Amount of federal taxes offset				$ 24,142
Decrease in sales and other operating revenues (as a percent)		12.00%
Number of facilities with an associated asset retirement obligation | facility	1
Other Income (Expense)
Loss Contingencies [Line Items]
Benefit of excise tax			$ 24,142
IPI Credit Bonus
Loss Contingencies [Line Items]
Gain contingency, unrecorded amount			$ 94,316
Tax Assessment | Brazilian State of Parana
Loss Contingencies [Line Items]
Loss contingency, estimate of possible loss	$ 12,041					$ 3,437
Tax Assessment | Brazilian State of Santa Catarina
Loss Contingencies [Line Items]
Loss contingency, estimate of possible loss	7,862				$ 2,973
Tax Assessment | Brazil State of Rio Grande do Sul and the State of Santa Catarina
Loss Contingencies [Line Items]
Loss contingency, estimate of possible loss	$ 10,782