Quarterly report pursuant to Section 13 or 15(d)

Basis of Presentation and Accounting Policies - Schedule of Deferred Revenues (Details)

v3.19.1
Basis of Presentation and Accounting Policies - Schedule of Deferred Revenues (Details) - USD ($)
$ in Thousands
3 Months Ended
Mar. 31, 2019
Mar. 31, 2018
Basis Of Presentation And Accounting Policies [Abstract]    
Balance at beginning of period $ 1,327 $ 10,104
Revenues deferred during the period 3,409 875
Revenues recognized during the period (1,135) (1,550)
Balance at end of period $ 3,601 $ 9,429