XML 49 R38.htm IDEA: XBRL DOCUMENT

Share Based Payments - Summary of Non-Employee Stock Options Required to be Accounted for As Liabilities (Detail) - Non-employee Stock Options - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Fair value of non-employee options at beginning of period	$ 2,637	$ 1,617
Exercise of non-employee options	(737)
Change in fair value of non-employee stock options during the period	(571)	162
Fair value of non-employee options at end of period	$ 1,329	$ 1,779