Commitments and Contingencies - Reorganization (Details) - Employee Severance [Member] - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2019
Restructuring Cost and Reserve [Line Items]
Severance costs	$ 4,600
Severance costs		$ 3,300	$ 7,871
Restructuring Reserve [Roll Forward]
Beginning balance		0	0
Expense		$ 3,300	7,871
Cash Payments			(7,809)
Ending balance			$ 62
Sales and marketing
Restructuring Cost and Reserve [Line Items]
Severance costs	400
Technology and development
Restructuring Cost and Reserve [Line Items]
Severance costs	900
General and administrative
Restructuring Cost and Reserve [Line Items]
Severance costs	$ 3,300