Supplemental Quarterly Infomation (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended												12 Months Ended
	Dec. 31, 2018	[1]	Sep. 30, 2018	[1]	Jun. 30, 2018	[1]	Mar. 31, 2018	[1]	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	[2]	Dec. 31, 2016	[2]
Supplemental Quarterly Information [Abstract]
Revenue from contract with customers	$ 664,700		$ 659,800		$ 655,200		$ 606,900		$ 580,500	$ 511,200	$ 477,600	$ 509,000	$ 2,586,627	$ 2,078,548		$ 1,862,891
Income (loss) from continuing operations before income taxes	106,200		146,800		82,300		97,000		2,400	(63,600)	(21,900)	154,900	432,338	71,802		(493,115)
Income (loss) from continuing operations	112,600		95,800		45,900		168,700		(284,800)	(66,300)	(17,300)	57,500	423,008	(310,936)		(273,943)
Net income (loss) including noncontrolling interest	111,800		93,900		45,500		168,300						419,486	(311,789)		(275,970)
Net income (loss) attributable to Murphy	$ 103,400		$ 93,900		$ 45,500		$ 168,300		$ (286,800)	$ (65,900)	$ (17,600)	$ 58,500	$ 411,094	$ (311,789)		$ (275,970)
Income (loss) from continuing operations per Common share, Basic	$ 0.60		$ 0.55		$ 0.26		$ 0.98		$ (1.65)	$ (0.38)	$ (0.10)	$ 0.33	$ 2.39	$ (1.81)		$ (1.59)
Income (loss) from continuing operations per Common share, Diluted	0.59		0.55		0.26		0.97		(1.65)	(0.38)	(0.10)	0.33	2.37	(1.81)		(1.59)
Net income (loss) per Common share, Basic	0.60		0.54		0.26		0.97		(1.66)	(0.38)	(0.10)	0.34	2.38	(1.81)		(1.60)
Net income (loss) per Common share, Diluted	0.59		0.54		0.26		0.96		(1.66)	(0.38)	(0.10)	0.34	2.36	(1.81)		(1.60)
Cash dividend per Common share	$ 0.25		$ 0.25		$ 0.25		$ 0.25		$ 0.25	$ 0.25	$ 0.25	$ 0.25	$ 1.00	$ 1.00		$ 1.20

[1] 2018 includes noncontrolling interest in MP GOM.

[2] Reclassified to conform to current presentation (see Note B).