Summary of Significant Accounting Policies - Antidilutive Securities (Details) - $ / shares shares in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Anti-dilutive securities
Anti-dilutive securities excluded from computation of earnings per share	5,852	4,150	5,078	4,029
Maximum
Anti-dilutive securities
Average stock price	$ 56.10	$ 56.10	$ 56.10	$ 56.10
Stock options
Anti-dilutive securities
Anti-dilutive securities excluded from computation of earnings per share	5,336	3,750	4,585	3,648
RSU
Anti-dilutive securities
Anti-dilutive securities excluded from computation of earnings per share	516	380	493	363
ESPP
Anti-dilutive securities
Anti-dilutive securities excluded from computation of earnings per share		20		18