XML 103 R48.htm IDEA: XBRL DOCUMENT v3.19.3.a.u2
Cash Equivalents And Restricted Cash And Securities (Summary Of Cash Equivalents And Restricted Securities) (Details) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Cash and Cash Equivalents [Line Items]        
Cash Equivalents, Cost Basis $ 34,294 $ 42,236 $ 40,753 $ 57,341
Restricted Securities, Cost Basis 528 747    
Money Market Funds [Member]        
Cash and Cash Equivalents [Line Items]        
Cash Equivalents, Cost Basis 1,472 1,445    
Restricted Securities, Cost Basis 528 747    
Unrealized Holding Gains (Losses)    
Cash Equivalents, Estimated Market Value 1,472 1,445    
Restricted Securities, Estimated Market Value $ 528 $ 747