Annual report pursuant to Section 13 and 15(d)

Leases (Percentage of Revenue) (Details)

v3.20.4
Leases (Percentage of Revenue) (Details) - United States Government - Concentration risk
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Lease Revenue, Risk Benchmark    
Concentration Risk [Line Items]    
Percentage of revenue 35.00% 34.00%
Fixed Lease Revenue Benchmark    
Concentration Risk [Line Items]    
Percentage of revenue 25.00% 25.00%