Annual report pursuant to Section 13 and 15(d)

Summary of Significant Accounting Policies (Properties and Impairment) (Details)

v3.20.4
Summary of Significant Accounting Policies (Properties and Impairment) (Details)
 12 Months Ended
Dec. 31, 2020
Properties  
Period after the cessation of major construction activities for considering property as operational if leases have not commenced earlier (in years) 1 year
Period after the cessation of major construction activities for considering property as partially operational if leases have commenced earlier (in years) 1 year
Property, Plant and Equipment [Line Items]  
Period used recovery analysis for long-lived assets to be held and used that may be impaired (in years) 10 years
Minimum | Buildings and building improvements  
Property, Plant and Equipment [Line Items]  
Estimated useful life 10 years
Minimum | Land improvements  
Property, Plant and Equipment [Line Items]  
Estimated useful life 10 years
Minimum | Equipment and personal property  
Property, Plant and Equipment [Line Items]  
Estimated useful life 3 years
Maximum | Buildings and building improvements  
Property, Plant and Equipment [Line Items]  
Estimated useful life 40 years
Maximum | Land improvements  
Property, Plant and Equipment [Line Items]  
Estimated useful life 20 years
Maximum | Equipment and personal property  
Property, Plant and Equipment [Line Items]  
Estimated useful life 10 years