v3.5.0.1
Business Segment Information (Geographic Data) (Details)
$ in Thousands
3 Months Ended 12 Months Ended
Mar. 31, 2016
USD ($)
Dec. 31, 2015
USD ($)
Sep. 30, 2015
USD ($)
Jun. 30, 2015
USD ($)
Mar. 31, 2015
USD ($)
Dec. 31, 2014
USD ($)
Sep. 30, 2014
USD ($)
Jun. 30, 2014
USD ($)
Mar. 31, 2016
USD ($)
geographic_area
Mar. 31, 2015
USD ($)
Mar. 31, 2014
USD ($)
Geographic Data                      
Number of geographic areas the Company operates in | geographic_area                 2    
Operating revenues $ 49,857 $ 55,144 $ 61,932 $ 56,108 $ 60,225 $ 60,145 $ 61,472 $ 63,338 $ 223,041 $ 245,180 $ 287,346
Assets 421,717       466,025       421,717 466,025  
United States of America                      
Geographic Data                      
Operating revenues                 217,349 234,554 275,161
Assets 415,422       458,197       415,422 458,197  
Europe                      
Geographic Data                      
Operating revenues                 5,692 10,626 $ 12,185
Assets $ 6,295       $ 7,828       $ 6,295 $ 7,828