Share-Based Payments - Summary of Stock Option Activity and Related Information (Details) - USD ($) $ / shares in Units, $ in Thousands		12 Months Ended
	Dec. 03, 2018	Dec. 31, 2018	Dec. 31, 2017
Number of Shares
Outstanding at beginning of period (in shares)		2,695,796
Granted (in shares)	425,000	3,545,900
Exercised (in shares)		(439,013)
Cancelled or forfeited (in shares)		(1,860,736)
Outstanding at end of period (in shares)		3,941,947	2,695,796
Exercisable at end of period (in shares)		938,968
Weighted-Average Exercise Price
Outstanding at beginning of period (in dollars per share)		$ 3.16
Granted (in dollars per share)		1.71
Exercised (in dollars per share)		0.62
Cancelled or forfeited (in dollars per share)		3.21
Outstanding at end of period (in dollars per share)		2.12	$ 3.16
Exercisable at end of period (in dollars per share)		$ 3.30
Remaining Contractual Life (in years)
Remaining contractual life of stock options outstanding		9 years 1 month 21 days	8 years 6 months 18 days
Exercisable at end of period		8 years 15 days
Outstanding intrinsic value beginning of period		$ 57	$ 146
Aggregate intrinsic value exercisable		$ 1