Weighted average amortization period of finite-lived intangible assets acquired either individually or as part of a group of assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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The amount of goodwill arising from a business combination that is expected to be deductible for tax purposes.

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This element represents the fair value of the noncontrolling interest in the acquiree at the acquisition date.

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Amount of liability recognized arising from contingent consideration in a business combination.

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Amount of other liabilities due within one year or within the normal operating cycle, if longer, assumed at the acquisition date.

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The number of businesses acquired by the entity during the period.

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Amount of cash inflow (outflow) from financing activities classified as other.

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Goodwill and Other Intangible Assets (2019 Acquisitions) (Narrative) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($) yr acquisition	Dec. 31, 2019 USD ($) acquisition	Dec. 31, 2018 USD ($)	Jun. 30, 2020
Business Combinations [Line Items]
Business combinations, number of acquisitions \| acquisition	5	6
Amounts due to former owners, subsequently paid	$ 11,790	$ 8,458	$ 0
Business combinations, contingent consideration liabilities, range of potential undiscounted earn-out liabilities, low	48,000
Business combinations, contingent consideration liabilities, range of potential undiscounted earn-out liabilities, high	$ 179,000
2019 Acquisitions [Member]
Business Combinations [Line Items]
Business combinations, acquired finite-lived intangible assets, weighted average lives (in years)	11 years
Business combinations, goodwill, expected tax deductible amount	$ 8,000
Business combinations, contingent consideration, earn-out liabilities	22,300
Business combinations, contingent consideration, mandatorily redeemable non-controlling interest	17,800
Business combinations, contingent consideration liabilities, range of potential undiscounted earn-out liabilities, low	4,000
Business combinations, contingent consideration liabilities, range of potential undiscounted earn-out liabilities, high	$ 51,000
2019 Acquisitions [Member] \| Customer Relationships [Member]
Business Combinations [Line Items]
Business combinations, acquired finite-lived intangible assets, weighted average lives (in years)	12 years
2019 Acquisitions [Member] \| Backlog [Member]
Business Combinations [Line Items]
Business combinations, acquired finite-lived intangible assets, weighted average lives (in years)	3 years
2019 Acquisitions [Member] \| Other Amortizing Intangible Assets [Member]
Business Combinations [Line Items]
Business combinations, acquired finite-lived intangible assets, weighted average lives (in years)	5 years
2019 Acquisitions [Member] \| Expected Term [Member]
Business Combinations [Line Items]
Business combinations, contingent consideration, earn-out period (in years) \| yr	5
Oil and Gas [Member]
Business Combinations [Line Items]
Business combinations, number of acquisitions \| acquisition		1
Communications [Member]
Business Combinations [Line Items]
Business combinations, number of acquisitions \| acquisition	1	4
Business combinations, percentage of interests acquired		96.00%
Clean Energy and Infrastructure
Business Combinations [Line Items]
Business combinations, number of acquisitions \| acquisition		1
Business combinations, percentage of interests acquired	91.00%			96.00%
Management [Member] \| 2019 Acquisitions [Member]
Business Combinations [Line Items]
Business combination, liabilities assumed, amounts due to former owners	$ 11,000
Amounts due to former owners, subsequently paid	$ 2,000