Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) shares in Millions, $ in Millions	Total	Revision of Prior Period Change in Accounting Principle Adjustment [Member]	RSUs [Member]	Class A Common stock [Member]	Class A Common stock [Member] RSUs [Member]	Additional Paid-In Capital [Member]	Treasury Stock [Member]	Treasury Stock [Member] RSUs [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Accumulated Deficit [Member]	Accumulated Deficit [Member] Revision of Prior Period Change in Accounting Principle Adjustment [Member]
Beginning balance, Value at Dec. 31, 2019	$ 1,975.4					$ 3,898.7			$ (125.9)	$ (1,797.4)
Beginning balance, Shares at Dec. 31, 2019				950.0
Exercise of stock options and ESPP	8.8					8.8
Exercise of stock options and ESPP, Shares				2.5
Vesting of RSUs, net of tax withholdings			$ (14.8)					$ (14.8)
Vesting of RSUs, net of tax withholdings, Shares					3.3
Stock-based compensation expense	20.5					20.5
Retirements of treasury stock							$ 14.8			(14.8)
Adoption of ASU 2016-13 | 2016-13		$ (0.4)									$ (0.4)
Net income (loss)	(103.9)									(103.9)
Other comprehensive income (loss)	(30.0)								(30.0)
Ending balance, Value at Mar. 31, 2020	1,855.6					3,928.0			(155.9)	(1,916.5)
Ending balance, Shares at Mar. 31, 2020				955.8
Beginning balance, Value at Dec. 31, 2020	2,941.5					5,276.5			(50.7)	(2,284.3)
Beginning balance, Shares at Dec. 31, 2020				1,081.6
Exercise of stock options and ESPP	10.5					10.5
Exercise of stock options and ESPP, Shares				2.7
Vesting of RSUs, net of tax withholdings			$ (8.2)					$ (8.2)
Vesting of RSUs, net of tax withholdings, Shares					4.5
Stock-based compensation expense	37.2					37.2
Retirements of treasury stock							$ 8.2			(8.2)
Net income (loss)	(23.0)									(23.0)
Other comprehensive income (loss)	(15.6)								(15.6)
Ending balance, Value at Mar. 31, 2021	$ 2,942.4					$ 5,324.2			$ (66.3)	$ (2,315.5)
Ending balance, Shares at Mar. 31, 2021				1,088.8