CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (unaudited) - USD ($) $ in Thousands	Total	Murphy Shareholders' Equity	Cumulative Preferred Stock	Common Stock	Capital In Excess Of Par Value	Retained Earnings	Retained Earnings Cumulative Effect, Period of Adoption, Adjustment	Accumulated Other Comprehensive Loss	Treasury Stock	Noncontrolling Interest
Balance at beginning of period at Dec. 31, 2018				$ 195,077	$ 979,642	$ 5,513,529	$ 116,768	$ (609,787)	$ (1,249,162)	$ 368,343
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options, including income tax benefits				6	(123)
Restricted stock transactions and other					(38,732)
Share-based compensation					25,041
Adjustments to acquisition valuation					(24,519)
Net (loss) income for the period	$ 1,307,713					1,221,456				86,257
Cash dividends						(125,437)
Foreign currency translation (loss) gain, net of income taxes	36,927							36,927
Retirement and postretirement benefit plans, net of income taxes								8,277
Deferred loss on interest rate hedges reclassified to interest expense, net of income taxes	1,756							1,756
Purchase of treasury shares									(405,938)
Awarded restricted stock, net of forfeitures									31,869
Acquisition closing adjustments										(7,920)
Distributions to noncontrolling interest owners										(97,510)
Balance at end of period at Sep. 30, 2019	6,025,820	$ 5,676,650	$ 0	195,083	941,309	6,726,316		(562,827)	(1,623,231)	349,170
Balance at beginning of period at Jun. 30, 2019				195,083	933,944	5,677,248		(549,045)	(1,517,217)	358,532
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based compensation					7,365
Net (loss) income for the period	1,111,702					1,089,002				22,700
Cash dividends						(39,934)
Foreign currency translation (loss) gain, net of income taxes	(17,128)							(17,128)
Retirement and postretirement benefit plans, net of income taxes								2,761
Deferred loss on interest rate hedges reclassified to interest expense, net of income taxes	585							585
Purchase of treasury shares									(106,014)
Acquisition closing adjustments										(3,328)
Distributions to noncontrolling interest owners										(28,734)
Balance at end of period at Sep. 30, 2019	6,025,820	5,676,650	0	195,083	941,309	6,726,316		(562,827)	(1,623,231)	349,170
Balance at beginning of period at Dec. 31, 2019	5,804,611			195,089	949,445	6,614,304		(574,161)	(1,717,217)	337,151
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options, including income tax benefits				12	(156)
Restricted stock transactions and other					(33,649)
Share-based compensation					20,678
Net (loss) income for the period	(1,099,710)					(976,841)				(122,869)
Cash dividends						(76,790)
Foreign currency translation (loss) gain, net of income taxes	(39,520)							(39,520)
Retirement and postretirement benefit plans, net of income taxes								(45,219)
Deferred loss on interest rate hedges reclassified to interest expense, net of income taxes	905							905
Awarded restricted stock, net of forfeitures									26,556
Distributions to noncontrolling interest owners										(43,673)
Balance at end of period at Sep. 30, 2020	4,514,045	4,343,436	0	195,101	936,318	5,560,673		(657,995)	(1,690,661)	170,609
Balance at beginning of period at Jun. 30, 2020				195,101	931,429	5,823,426		(690,341)	(1,691,070)	204,937
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Restricted stock transactions and other					(409)
Share-based compensation					5,298
Net (loss) income for the period	(266,608)					(243,553)				(23,055)
Cash dividends						(19,200)
Foreign currency translation (loss) gain, net of income taxes	28,323							28,323
Retirement and postretirement benefit plans, net of income taxes								3,726
Deferred loss on interest rate hedges reclassified to interest expense, net of income taxes	297							297
Awarded restricted stock, net of forfeitures									409
Distributions to noncontrolling interest owners										(11,273)
Balance at end of period at Sep. 30, 2020	$ 4,514,045	$ 4,343,436	$ 0	$ 195,101	$ 936,318	$ 5,560,673		$ (657,995)	$ (1,690,661)	$ 170,609