Summary of Significant Accounting Policies, Income Taxes (Details) $ in Millions	3 Months Ended	12 Months Ended
Dec. 31, 2018 USD ($)	Dec. 31, 2018 USD ($)
Income tax
Undistributed foreign earnings	$ 800.0	$ 800.0
Income tax benefit	$ 14.5	$ 14.5

Amount of undistributed earnings of foreign subsidiaries intended to be permanently reinvested outside the country of domicile.

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