CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (UNAUDITED) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Income Statement [Abstract]
Revenue	$ 58,853	$ 28,222	$ 112,083	$ 73,731
Costs and expenses:
Partner Share and other third-party costs	29,953	16,811	59,724	42,949
Delivery costs	5,748	3,499	9,686	6,905
Sales and marketing expense	17,063	10,405	30,265	21,373
Research and development expense	8,934	3,966	15,152	7,817
General and administration expense	16,888	11,734	29,063	22,478
Acquisition and integration costs	14,182	0	21,212	0
Depreciation and amortization expense	8,833	1,545	11,898	3,876
Total costs and expenses	101,601	47,960	177,000	105,398
Operating loss	(42,748)	(19,738)	(64,917)	(31,667)
Other (expense) income:
Interest (expense) income, net	(3,078)	(10)	(6,123)	274
Change in fair value of contingent consideration	(1,480)	0	(1,480)	0
Foreign currency (loss) gain	0	(10)	319	(1,896)
Total other expense	(4,558)	(20)	(7,284)	(1,622)
Loss before income taxes	(47,306)	(19,758)	(72,201)	(33,289)
Income tax benefit	0	0	0	0
Net loss	(47,306)	(19,758)	(72,201)	(33,289)
Net loss attributable to common stockholders	$ (47,306)	$ (19,758)	$ (72,201)	$ (33,289)
Net loss per share attributable to common stockholders, basic and diluted (in USD per share)	$ (1.43)	$ (0.73)	$ (2.32)	$ (1.24)
Weighted-average common shares outstanding, basic and diluted (in shares)	32,977	27,072	31,145	26,898