Deferred Revenues and Customer Advances (Tables)
|12 Months Ended|
Dec. 31, 2017
|Deferred Revenues and Customer Advances [Abstract]|
|Schedule of deferred revenues and customer advances||
Tabular disclosure of the type of arrangements and the corresponding amounts that comprise the current and noncurrent balance of deferred revenue as of the balance sheet date.
Reference 1: http://www.xbrl.org/2003/role/presentationRef