Revenue - Contract Balances (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Revenue from Contract with Customer [Abstract]
Accounts receivable, net	$ 39,972	$ 37,655
Deferred contract acquisition costs, current	14,317	13,014
Deferred contract acquisition costs, non-current	34,047	30,655
Total deferred contract acquisition costs	48,364	43,669
Contract assets (included in prepaid expenses and other current assets)	623	825
Contract liabilities (deferred revenue)	25,632	24,681
Contract liabilities (deferred revenue) (included in other long-term liabilities)	3,978	1,550
Net contract assets (liabilities)	$ (28,987)	$ (25,406)