Acquisitions (Narrative) (Details) $ in Thousands	1 Months Ended	3 Months Ended		7 Months Ended
	Jun. 30, 2019 USD ($)	Mar. 31, 2020 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2019 USD ($)	May 31, 2019 MMBoe
Business Acquisition [Line Items]
Revenue from sales to customers		$ 600,558	$ 629,354
Income (loss) from continuing operations before income taxes		(595,373)	33,745
Impairment of assets		967,530	$ 0
LLOG Exploration Offshore L.L.C. and LLOG Bluewater Holdings, L.L.C.
Business Acquisition [Line Items]
Proved reserves | MMBoe					67
Cash consideration paid to PAI	$ 1,236,200			$ 1,236,165
Revenue from sales to customers		93,700
Income (loss) from continuing operations before income taxes		(406,300)
Impairment of assets		$ 413,200
LLOG Exploration Offshore L.L.C. and LLOG Bluewater Holdings, L.L.C. | Sales Thresholds 2019 to 2022
Business Acquisition [Line Items]
Contingent consideration, maximum				200,000
LLOG Exploration Offshore L.L.C. and LLOG Bluewater Holdings, L.L.C. | First Oil from Development Projects
Business Acquisition [Line Items]
Contingent consideration, maximum				$ 50,000