Significant Accounting Polices - Additional Information (Details) - shares	3 Months Ended
Mar. 31, 2018	Mar. 31, 2017
Accounting Policies [Abstract]
Options granted	62,500	0

Gross number of share options (or share units) granted during the period.

No definition available.

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration