Capitalized Exploratory Well Costs (Tables)

12 Months Ended

Dec. 31, 2013

Projects with Exploratory Well Costs Capitalized for More than One Year [Line Items]

Capitalized Exploratory Well Costs, Roll Forward [Table Text Block]

	2013			2012			2011
	(in millions)
Balance at January 1,	$	2.1		$	5.0		$	13.6
Additions to capitalized exploratory well costs pending the determination of proved reserves	2.7			12.7			—
Reclassifications to proved properties after the determination of proved reserves	(2.2		)	(15.6		)	(8.3		)
Capitalized exploratory well costs charged to expense	—			—			(0.3		)
Balance at December 31,	$	2.6		$	2.1		$	5.0