Valuation Accounts and Reserves (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Allowance for doubtful accounts [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at January 1			$ 6.7		$ 7.9
Charged (Credited) to Expense			0.4		0.3
Deductions			(0.4)		(1.5)
Other			(5.1)	[1]
Balance at December 31	1.6		1.6		6.7
Deferred tax asset valuation allowance [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at January 1	633.7		524.0		445.8
Charged (Credited) to Expense	37.7		115.4		78.2
Other	(364.9)	[1]	(5.7)	[1]
Balance at December 31	$ 306.5		$ 633.7		$ 524.0

[1] 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.