Selected Quarterly Financial Data (Unaudited) (Tables)

12 Months Ended

Dec. 31, 2017

Quarterly Financial Information Disclosure [Abstract]

Selected Unaudited Quarterly Consolidated Statements of Operations Data

The following tables set forth selected unaudited quarterly consolidated statements of operations data for each of the eight quarters in the years ended December 31, 2017 and 2016 (in thousands except per share data):

	Quarter ended
	Dec 31,2017			Sept 30, 2017			June 30, 2017			Mar 31, 2017			Dec 31, 2016			Sept 30, 2016			June 30, 2016			Mar 31, 2016
Consolidated Statements of    Operations Data
Revenues	$	140,535		$	129,764		$	119,436		$	111,791		$	104,503		$	96,839		$	91,844		$	86,538
Gross profit		106,915			98,980			89,875			84,485			79,851			73,384			69,480			64,798
Operating loss		(6,185	)		(6,246	)		(7,543	)		(7,301	)		(6,606	)		(7,061	)		(6,304	)		(5,981	)
Net loss		(6,089	)		(5,712	)		(7,031	)		(7,309	)		(6,946	)		(7,979	)		(7,771	)		(6,613	)
Net loss per share, basic and    diluted	$	(0.08	)	$	(0.07	)	$	(0.09	)	$	(0.10	)	$	(0.09	)	$	(0.11	)	$	(0.11	)	$	(0.09	)