XML 45 R35.htm IDEA: XBRL DOCUMENT v3.8.0.1
Cash Equivalents And Restricted Securities (Summary Of Cash Equivalents And Restricted Securities) (Details) - USD ($)
$ in Thousands
9 Months Ended 12 Months Ended
Sep. 30, 2017
Dec. 31, 2016
Sep. 30, 2016
Dec. 31, 2015
Cash and Cash Equivalents [Line Items]        
Cash Equivalents, Cost Basis $ 54,242 $ 56,642 $ 54,131 $ 37,588
Restricted Securities, Cost Basis 771 699    
Money Market Funds [Member]        
Cash and Cash Equivalents [Line Items]        
Cash Equivalents, Cost Basis 371 3,466    
Restricted Securities, Cost Basis 771 699    
Unrealized Holding Gains    
Cash Equivalents, Estimated Market Value 371 3,466    
Restricted Securities, Estimated Market Value $ 771 $ 699