THE COMPANY AND SIGNIFICANT ACCOUNTING POLICIES - Increase (decrease) in cash equivalents and restricted (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Cash flows from operating activities:
Net cash provided by (used in) operating activities	$ 46.5	$ (113.9)	$ (233.8)	$ (312.9)	$ (614.1)	$ (1,129.5)	$ 579.0
Cash flows from investing activities:
Net cash used in investing activities	(36.9)	(28.8)	13.5	(16.0)	(68.2)	(154.6)	(516.1)
Cash flows from financing activities:
Net cash provided by (used in) financing activities	(27.9)	(48.3)	1,212.2	854.7	1,990.7	1,330.3	(112.9)
Effect of exchange rate changes on cash and cash equivalents and restricted cash	(1.6)	(8.4)	5.6	(5.1)	(9.5)	(0.3)	1.5
Net increase (decrease) in cash and cash equivalents and restricted cash	(19.9)	(199.4)	997.5	520.7	1,298.9	45.9	(48.5)
Cash and cash equivalents and restricted cash at beginning of period	1,640.2	1,839.6	842.1	321.4	321.4	275.5	324.0
Cash and cash equivalents and restricted cash at end of period	$ 1,620.3	$ 1,640.2	$ 1,839.6	$ 842.1	$ 1,620.3	$ 321.4	$ 275.5

Amount of cash and cash equivalents, and cash and cash equivalents restricted to withdrawal or usage. Excludes amount for disposal group and discontinued operations. Cash includes, but is not limited to, currency on hand, demand deposits with banks or financial institutions, and other accounts with general characteristics of demand deposits. Cash equivalents include, but are not limited to, short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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