Amount of net tax benefit (deficiency) from vesting of share-based payment awards.

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Projects gains are defined as project revenue, less project costs of revenue, including project-related depreciation, in particular, on construction contracts accounted for under the cost-to-cost method, for which the recorded amounts require estimates of costs to complete.

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Amount of loss from the write-down of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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Amount of impairment loss resulting from write-down of assets, excluding financial assets and goodwill, lacking physical substance and having a projected indefinite period of benefit to fair value.

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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 increase (decrease) in the income tax rates.

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Amount of income tax expense (benefit) from effect of Tax Cuts and Jobs Act.

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Quarterly Information (Unaudited) (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended						12 Months Ended
	Dec. 31, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Quarterly Financial Information [Line Items]
Intangible asset, pre-tax impairment charge							$ 3.3
Goodwill, pre-tax impairment charge				$ 47.7				$ 47.7
Stock-based compensation, net excess tax benefits	$ 1.6		$ 2.3	1.3			3.9	1.6	$ 5.4
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount	(5.9)	$ (1.4)
Change in tax rate, non-cash tax (expense) benefit				$ (3.7)	$ 17.9	$ (1.5)		16.4	$ 120.1
Joint Venture [Member]
Quarterly Financial Information [Line Items]
Project gains						$ 1.0		$ 1.0
Pre-Qualifications [Member]
Quarterly Financial Information [Line Items]
Intangible asset, pre-tax impairment charge	$ 3.3						$ 3.3