Cash and Cash Equivalents (Tables)

12 Months Ended

Dec. 31, 2017

Cash And Cash Equivalents [Abstract]

Summary of Cash and Cash Equivalents

	As of December 31,
	2016		2017
	$		$
Cash at bank and in hand		36,531,272		204,008,828
Cash equivalents		47,417,498		25,651,320
		83,948,770		229,660,148
Denominated in:
US$		77,463,141		224,878,393
RMB (note (i))		6,365,311		3,927,163
Australia dollar ("A$")		120,318		854,592
		83,948,770		229,660,148