Common Stock and Stock-Based Compensation - Options Activity (Details) shares in Thousands	6 Months Ended
	Jun. 30, 2019 $ / shares shares
Shares (in thousands)
Options outstanding, beginning of period (in shares) | shares	3,744
Granted (in shares) | shares	924
Exercised (in shares) | shares	(386)
Canceled (in shares) | shares	(46)
Options outstanding, end of period (in shares) | shares	4,236
Weighted- Average Exercise Price per Share
Outstanding weighted average exercise price, beginning balance (in usd per share) | $ / shares	$ 20.69
Granted weighted average exercise price (in usd per share | $ / shares	50.28
Exercised weighted average exercise price (in usd per share | $ / shares	14.83
Canceled weighted average exercise price (in usd per share | $ / shares	34.57
Outstanding weighted average exercise price, ending balance (in usd per share | $ / shares	$ 27.53