Changes in SAR Outstanding (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding at end of year	6,006,585
Stock Appreciation Rights (SAR) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding at beginning of year	0
Number of SAR, Granted	851,000
Number of SAR, Forfeited	(68,712)
Number of SAR, Murphy USA Inc. spin-off adjustment	78,824
Outstanding at end of year	788,112
Forfeited
Surrendered in connection with separation of Murphy USA Inc.
Murphy USA Inc. spin-off adjustment
Outstanding at end of year	$ 54.21
Forfeited
Surrendered in connection with separation of Murphy USA Inc.
Murphy USA Inc. spin-off adjustment
Stock Appreciation Rights (SAR) [Member] | Spin [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of SAR, Forfeited	(73,000)