Income Taxes - Unrecognized Tax Benefits and Effect on Effective Income Tax Rate (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Beginning balance of unrecognized tax benefits	$ 356.4	$ 214.3	$ 162.6
Additions for tax positions of current year	3.4	106.0	7.3
Additions for tax positions of prior years	47.9	59.5	49.3
Reductions for tax positions of prior years	(16.0)	(7.0)	(4.3)
Reductions for lapses of statutes of limitation and settlements	(1.4)	(16.4)	(0.6)
Ending balance of unrecognized tax benefits	$ 390.3	$ 356.4	$ 214.3

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

No definition available.

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- Definition

Amount of unrecognized tax benefits.

+ References

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Amount of decrease in unrecognized tax benefits resulting from tax positions taken in prior period tax returns.

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Amount of increase in unrecognized tax benefits resulting from tax positions that have been or will be taken in current period tax return.

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