Consolidated Statements of Operations (Unaudited) - USD ($) shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Revenue:
Total revenue	$ 704.7	$ 503.3	$ 2,105.0	$ 1,358.8
Costs and expenses:
Cost of revenue	240.8	235.9	754.8	561.4
Research and development	143.5	165.9	394.0	591.7
Sales and marketing	216.7	187.0	709.6	444.8
General and administrative	49.2	36.1	122.8	103.5
Impairment related to real estate assets	66.8		66.8
Total costs and expenses	717.0	624.9	2,048.0	1,701.4
Income (loss) from operations	(12.3)	(121.6)	57.0	(342.6)
Interest income	1.6	1.0	5.0	10.2
Interest expense	(14.8)	(7.3)	(44.2)	(21.2)
Other income (expense), net	(0.6)	(3.1)	(0.8)	(4.9)
Income (loss) before income taxes	(26.1)	(131.0)	17.0	(358.5)
Provision for (benefit from) income taxes	15.6	(8.8)	53.9	17.9
Net income (loss)	$ (41.7)	$ (122.2)	$ (36.9)	$ (376.4)
Net income (loss) per share attributable to common stockholders:
Basic	$ (0.04)	$ (0.11)	$ (0.03)	$ (0.38)
Diluted	$ (0.04)	$ (0.11)	$ (0.03)	$ (0.38)
Weighted-average common shares used to compute net income (loss) per share attributable to common stockholders:
Basic	1,097.1	1,076.7	1,090.4	995.6
Diluted	1,097.1	1,076.7	1,090.4	995.6
Online Game [Member]
Revenue:
Total revenue	$ 571.1	$ 436.0	$ 1,715.1	$ 1,168.6
Advertising and Other [Member]
Revenue:
Total revenue	$ 133.6	$ 67.3	$ 389.9	$ 190.2