|12 Months Ended|
Dec. 31, 2017
|Payables and Accruals [Abstract]|
8. Accrued liabilities
Accrued liabilities consist of the following (in thousands).
The entire disclosure for accounts payable and accrued liabilities at the end of the reporting period.
Reference 1: http://www.xbrl.org/2003/role/presentationRef