Revenue - Disaggregation and Other (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Revenue
Revenue	$ 241,030	$ 130,276	$ 421,829	$ 258,849
Accounts receivable, net of allowance for doubtful accounts	76,902		76,902		$ 56,948
Net increase in deferred revenue			12,300	4,600
Member refunds issued relating to Company's direct-to-consumer behavioral health products	2,400	600	3,700	1,200
United States | Subscription Access Fees
Revenue
Revenue	152,021	85,530	259,960	166,509
United States | Paid Visits
Revenue
Revenue	39,041	15,083	69,939	33,331
United States | Visit Fee Only
Revenue
Revenue	19,471	3,546	32,057	7,667
Foreign.
Revenue
Revenue	30,500	26,100	59,900	51,300
Foreign. | Subscription Access Fees
Revenue
Revenue	30,150	25,711	59,264	50,686
Foreign. | Paid Visits
Revenue
Revenue	$ 347	$ 406	$ 609	$ 656