Contingencies and Other Information - Narrative (Details) $ in Thousands	12 Months Ended		24 Months Ended
	Mar. 31, 2020 USD ($) facility	Mar. 31, 2013 USD ($)	Dec. 31, 2005 USD ($)	Mar. 18, 2014 USD ($)	Oct. 26, 2007 USD ($)
Loss Contingencies [Line Items]
Amount of federal taxes offset			$ 24,142
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	$ 9,039				$ 2,534
Tax Assessment | Brazilian State of Santa Catarina
Loss Contingencies [Line Items]
Loss contingency, estimate of possible loss	5,875			$ 2,192
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	$ 9,378