Capitalized Exploratory Well Costs (Tables)

9 Months Ended

Sep. 30, 2017

Capitalized Exploratory Well Costs [Abstract]

Capitalized Exploratory Well Costs [Table Text Block]

Net changes in capitalized exploratory well costs are presented in the table below.

	Capitalized Exploratory Well Costs
	2017
	(in millions)
Balance at January 1,	$	14.2
Additions to capitalized exploratory well costs	10.6
Reclassifications to proved properties	(3.6		)
Capitalized exploratory well costs charged to expense	(21.2		)
Balance at September 30,	$	—