Shareholders' Equity (Reclassification out of Accumulated Other Comprehensive Income) (Parenthetical) (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Total expense from discontinued operations, net of tax expense	$ 12.0	$ 8.2	$ 3.6

Amount of tax expense (benefit) attributable to income (loss) from operations classified as a discontinued operation. Excludes tax expense (benefit) for gain (loss) on disposal and for provision for gain (loss) until disposal.

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