Related Party Transactions - IPO Participation (Details) - Management - Participation in IPO $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($) $ / shares shares
Related Party Transaction [Line Items]
Percentage of shares purchased	5.00%
Offering price per share (in dollars per share) | $ / shares	$ 15.00
Total Purchase Price	$ 50,000
John T Chambers
Related Party Transaction [Line Items]
Shares of Class A Common Stock | shares	333,333
Total Purchase Price	$ 5,000
L. John Doerr
Related Party Transaction [Line Items]
Shares of Class A Common Stock | shares	1,333,333
Total Purchase Price	$ 20,000
General Colin L. Powell
Related Party Transaction [Line Items]
Shares of Class A Common Stock | shares	333,333
Total Purchase Price	$ 5,000
New Enterprise Associates
Related Party Transaction [Line Items]
Shares of Class A Common Stock | shares	1,333,333
Total Purchase Price	$ 20,000