Quarterly report pursuant to Section 13 or 15(d)

Fair Value Measurements (Recurring) (Details)

v3.20.2
Fair Value Measurements (Recurring) (Details) - Fair Value, Recurring [Member] - USD ($)
$ in Thousands
Jun. 30, 2020
Dec. 31, 2019
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Total assets $ 339,156 $ 1,018
Total liabilities 6,598 1,442
Fair Value, Inputs, Level 1 [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Total assets 339,156 0
Total liabilities 0 0
Fair Value, Inputs, Level 2 [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Total assets 0 1,018
Total liabilities 6,598 1,442
Fair Value, Inputs, Level 3 [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Total assets 0 0
Total liabilities 0 0
Short-term government securities [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Short-term government securities (cash and cash equivalents) 339,156  
Short-term government securities [Member] | Fair Value, Inputs, Level 1 [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Short-term government securities (cash and cash equivalents) 339,156  
Short-term government securities [Member] | Fair Value, Inputs, Level 2 [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Short-term government securities (cash and cash equivalents) 0  
Short-term government securities [Member] | Fair Value, Inputs, Level 3 [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Short-term government securities (cash and cash equivalents) 0  
Interest Rate Swap [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Interest rate swaps (prepaids and other assets)   1,018
Interest rate swaps (other liabilities) 6,598 1,442
Interest Rate Swap [Member] | Fair Value, Inputs, Level 1 [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Interest rate swaps (prepaids and other assets)   0
Interest rate swaps (other liabilities) 0 0
Interest Rate Swap [Member] | Fair Value, Inputs, Level 2 [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Interest rate swaps (prepaids and other assets)   1,018
Interest rate swaps (other liabilities) 6,598 1,442
Interest Rate Swap [Member] | Fair Value, Inputs, Level 3 [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Interest rate swaps (prepaids and other assets)   0
Interest rate swaps (other liabilities) $ 0 $ 0