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Summary of Significant Accounting Policies - Additional Information (Narrative) (Details)
 12 Months Ended
Dec. 31, 2020
Summary Of Significant Accounting Policies [Line Items]  
Cash equivalents maximum maturity period of highly liquid investments 90 days
Minimum [Member]  
Summary Of Significant Accounting Policies [Line Items]  
Number of business days for related transactions 1 day
Minimum [Member] | Notes Receivable  
Summary Of Significant Accounting Policies [Line Items]  
Service Period 3 years
Minimum [Member] | Property, Plant and Equipment  
Summary Of Significant Accounting Policies [Line Items]  
Service Period 3 years
Maximum [Member]  
Summary Of Significant Accounting Policies [Line Items]  
Number of business days for related transactions 2 days
Maximum [Member] | Notes Receivable  
Summary Of Significant Accounting Policies [Line Items]  
Service Period 10 years
Maximum [Member] | Property, Plant and Equipment  
Summary Of Significant Accounting Policies [Line Items]  
Service Period 7 years
Securities  
Summary Of Significant Accounting Policies [Line Items]  
Number of business days for related transactions 2 days
Commodities  
Summary Of Significant Accounting Policies [Line Items]  
Number of business days for related transactions 1 day