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Dispositions - Narrative (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
Dispositions - Narrative (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2020
Chevron \| Disposed of by Sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain on disposal	$ 152.8
Masternaut
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Impairment loss on investment		$ 15.7
Cumulative impairment loss on investments			$ 136.3