Annual report pursuant to Section 13 and 15(d)

Related Person Transactions (Details)

v3.8.0.1
Related Person Transactions (Details) - USD ($)
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Related Party Transaction [Line Items]      
Rental service charge $ 6,000 $ 12,000 $ 12,000
Purchase of maintenance and other services $ 110,000 $ 254,000 $ 313,000