Sale of Energy, Chemicals and Resources ("ECR") Business - Narrative (Details) - USD ($) $ in Thousands, shares in Millions			3 Months Ended		6 Months Ended		8 Months Ended	12 Months Ended
	Mar. 27, 2020	Apr. 26, 2019	Mar. 27, 2020	Mar. 29, 2019	Mar. 27, 2020	Mar. 29, 2019	Dec. 31, 2019	Sep. 27, 2019
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Selling, general and administrative expenses			$ 480,357	$ 514,160	$ 973,582	$ 969,551
Debt and Equity Securities, Gain (Loss)					(270,225)	0
NPMC
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Selling, general and administrative expenses					50,000
Worley
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Consideration transferred		$ 3,400,000
Consideration paid in cash		2,800,000
TSA related income			2,200		14,200
Worley | Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Pre-tax gain on sale		1,000,000
Gain on sale of businesses			19,967	$ 0	81,910	$ 0		$ 935,100
Fair value of retained interest		33,000
Deferred gain on disposal		34,400
Proceeds received on a relative fair value basis		$ 95,300
Worley Stock
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Ordinary shares included in purchase price (in shares)		58.2
Sale of stock (in shares)							6.8
Loss on sale of stock							$ 4,900
Worley Stock | Restricted Stock
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Ordinary shares included in purchase price (in shares)							51.4
Estimated fair value of shares	$ 180,900
Dividends					7,700
Debt and Equity Securities, Gain (Loss)			$ (375,500)		$ (270,200)