Amount of gain (loss) from sale and disposal of integrated set of activities and assets capable of being conducted and managed for purpose of providing return in form of dividend, lower cost, or other economic benefit to investor, owner, member and participant.

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Amount of income (loss) from continuing operations before deduction of income tax expense (benefit) and income (loss) attributable to noncontrolling interest, and addition of income (loss) from equity method investments.

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The cash inflow associated with the amount received from the sale of a portion of the company's business, for example a segment, division, branch or other business, during the period.

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Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

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Subsequent event (Details) - USD ($) $ in Millions	3 Months Ended								6 Months Ended	12 Months Ended
Subsequent event (Details) - USD ($) $ in Millions	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Subsequent Event [Line Items]
Revenue	$ 741.5	$ 757.6	$ 753.8	$ 695.8	$ 760.9	$ 688.3	$ 667.4	$ 708.4		$ 2,948.7	$ 2,825.0	$ 2,741.8
Pretax income	$ (5.7)	$ 6.5	$ 41.9	$ (3.0)	$ 38.1	$ 22.2	$ 20.3	$ 62.6		39.7	$ 143.2	$ (72.1)
U.S. Federal Business
Subsequent Event [Line Items]
Revenue										725.0
Pretax income										$ 100.0
Subsequent Event \| Forecast \| Discontinued Operation, Disposed of by Sale \| U.S. Federal Business
Subsequent Event [Line Items]
Cash purchase price									$ 1,200.0
After-tax gain on sale of discontinued operation									$ 1,000.0