Income Taxes (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Income Tax Disclosure [Abstract]
Provision for income taxes	$ 117.5	$ 116.8	$ 222.6	$ 218.9
Effective tax rate (percentage)	23.20%	23.00%	23.20%	22.10%
Effective income tax rate reconciliation, tax credit, foreign, amount	$ 7.5		$ 12.5
Effective income tax rate reconciliation, change in accounting method, amount				$ 22.6
Provision for income taxes, adjustments to initial estimate impact of TCJA				$ (15.8)

Effective Income Tax Rate Reconciliation, Change In Accounting Method, Amount

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Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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Amount of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to foreign tax credit.

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Amount of income tax expense (benefit) for measurement period adjustment from accounting for tax effect pursuant to Tax Cuts and Jobs Act.

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