Revenue Recognition - Disaggregation of Revenue By Major Product Category (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 64.9	$ 114.0	$ 133.4	$ 212.3
Lithium Hydroxide
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	33.8	68.4	71.5	125.3
Butyllithium
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	21.3	24.7	42.8	51.6
High Purity Lithium Metal and Other Specialty Compounds
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	4.2	14.1	12.2	27.1
Lithium Carbonate and Lithium Chloride
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 5.6	$ 6.8	$ 6.9	$ 8.3