Quarterly report pursuant to Section 13 or 15(d)

Fair Value Measurements - Assets and Liabilities Measured on a Recurring Basis (Details)

v3.21.1
Fair Value Measurements - Assets and Liabilities Measured on a Recurring Basis (Details) - USD ($)
$ in Thousands
Mar. 31, 2021
Dec. 31, 2020
Assets:    
Investments $ 204,271 $ 150,359
Total 360,862 422,709
Deposits held with banks    
Assets:    
Cash and cash equivalents: 110,050 130,807
Short-term highly liquid investments    
Assets:    
Cash and cash equivalents: 46,541 141,543
Level 1    
Assets:    
Investments 133,907 69,746
Total 290,468 342,096
Level 1 | Deposits held with banks    
Assets:    
Cash and cash equivalents: 110,050 130,807
Level 1 | Short-term highly liquid investments    
Assets:    
Cash and cash equivalents: 46,511 141,543
Level 2    
Assets:    
Investments 70,364 80,613
Total 70,394 80,613
Level 2 | Deposits held with banks    
Assets:    
Cash and cash equivalents: 0 0
Level 2 | Short-term highly liquid investments    
Assets:    
Cash and cash equivalents: 30 0
Level 3    
Assets:    
Investments 0
Total 0 0
Level 3 | Deposits held with banks    
Assets:    
Cash and cash equivalents: 0 0
Level 3 | Short-term highly liquid investments    
Assets:    
Cash and cash equivalents: $ 0 $ 0