Prepaid Expenses and Other Current Assets (Tables)

9 Months Ended

12 Months Ended

Sep. 30, 2019

Dec. 31, 2018

Prepaid Expense and Other Assets, Current [Abstract]

Summary of Prepaids and Other Current Assets

Prepaids and other current assets consisted of the following as of December 31, 2018 and September 30, 2019:

	December 31, 2018		September 30, 2019
	(in thousands)
Prepaid inventory	$	2,284	$	2,329
Restricted cash		550		307
Prepaid insurance		434		2,904
Deferred offering costs		1,218		—
Other		932		1,196
Prepaid and other current assets	$	5,418	$	6,736

Prepaids and other current assets consisted of the following as of December 31, 2017 and 2018:

	December 31, 2017		December 31, 2018
Prepaid inventory	$	2,230	$	2,284
Restricted cash		250		550
Deferred offering costs		—		1,218
Other		537		1,366
Prepaid and other current assets	$	3,017	$	5,418