Annual report pursuant to Section 13 and 15(d)

Segment Reporting (Narrative) (Details)

v3.10.0.1
Segment Reporting (Narrative) (Details)
3 Months Ended 12 Months Ended
Dec. 31, 2018
USD ($)
Sep. 30, 2018
USD ($)
Jun. 30, 2018
USD ($)
Mar. 31, 2018
USD ($)
Dec. 31, 2017
USD ($)
Sep. 30, 2017
USD ($)
Jun. 30, 2017
USD ($)
Mar. 31, 2017
USD ($)
Dec. 31, 2018
USD ($)
segment
Dec. 31, 2017
USD ($)
Dec. 31, 2016
USD ($)
Segment Reporting Information [Line Items]                      
Number of business segments | segment                 2    
Total revenues $ 132,936,000 $ 132,114,000 $ 126,589,000 $ 138,967,000 $ 143,529,000 $ 160,018,000 $ 162,766,000 $ 149,887,000 $ 530,606,000 $ 616,200,000 $ 613,398,000
Foreign Locations [Member]                      
Segment Reporting Information [Line Items]                      
Total revenues                 0 0 $ 0
Long lived assets $ 0       $ 0       $ 0 $ 0