Common Stock and Stockholders' Equity - Employee Stock Purchase Plan (Details) - USD ($) $ in Thousands		1 Months Ended	3 Months Ended			6 Months Ended
	May 08, 2017	Jul. 31, 2015	Jun. 30, 2017	Jun. 30, 2016	Mar. 31, 2016	Jun. 30, 2017	Jun. 30, 2016
Employee Stock Purchase Plan
Stock-based compensation			$ 4,565	$ 1,634		$ 7,662	$ 2,922
ESPP
Employee Stock Purchase Plan
Shares reserved for issuance under the plan (in shares)		458,024	367,056			367,056
Maximum offering period		27 months
Stock purchase price as a percentage of fair value (as a percent)		85.00%
Issuance of common stock under employee stock purchase plan (in shares)	90,968
Stock-based compensation			$ 100		$ 0	$ 300	$ 0