Significant Accounting Polices - Additional Information (Details) - shares	3 Months Ended	6 Months Ended
Jun. 30, 2017	Jun. 30, 2018
Accounting Policies [Abstract]
Options granted	0	202,500

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