Statement of Cash Flows - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash and Cash Equivalents [Abstract]
Accrued capital expenditures	$ 83.6	$ 133.7	$ 54.5

Future cash outflow to pay for purchases of fixed assets that have occurred.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
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-Section 50
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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