Revenue - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Disaggregation of Revenue [Line Items]
Revenue	$ 90,332	$ 52,000	$ 145,398	$ 101,513
Revenue, as a percent	100.00%	100.00%	100.00%	100.00%
Video
Disaggregation of Revenue [Line Items]
Revenue	$ 61,350	$ 21,279	$ 89,983	$ 41,508
Revenue, as a percent	67.90%	40.90%	61.90%	40.90%
Subscription and other in-app products
Disaggregation of Revenue [Line Items]
Revenue	$ 20,031	$ 15,642	$ 34,426	$ 31,238
Revenue, as a percent	22.20%	30.10%	23.70%	30.80%
Total user pay revenue
Disaggregation of Revenue [Line Items]
Revenue	$ 81,381	$ 36,921	$ 124,409	$ 72,746
Revenue, as a percent	90.10%	71.00%	85.60%	71.70%
Advertising revenue
Disaggregation of Revenue [Line Items]
Revenue	$ 8,951	$ 15,079	$ 20,989	$ 28,767
Revenue, as a percent	9.90%	29.00%	14.40%	28.30%