Valuation Accounts and Reserves (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Allowance for doubtful accounts [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at January 1		$ 1.6	$ 1.6	$ 6.7
Charged (Credited) to Expense				0.4
Deductions				(0.4)
Other	[1]			(5.1)
Balance at December 31		1.6	1.6	1.6
Deferred tax asset valuation allowance [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at January 1		306.5	633.7	524.0
Charged (Credited) to Expense		40.8	37.7	115.4
Other	[1]	(52.9)	(364.9)	(5.7)
Balance at December 31		$ 294.4	$ 306.5	$ 633.7

[1] Amount in 2015 for deferred tax asset valuation allowance is primarily associated with utilization of foreign tax credit carry forwards. Amount in 2014 for deferred tax asset valuation allowance is primarily associated with final abandonment of certain foreign investments in 2014, essentially offsetting changes in deferred tax assets. Amounts in 2013 primarily arose due to separation of Murphy USA Inc. and presentation of U.K. downstream operations as assets held for sale.