Capitalized Exploratory Well Costs (Tables)

6 Months Ended

Jun. 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. The balance at June 30, 2017, represents the amount of capitalized exploratory well costs that are pending the determination of proved reserves.

	Capitalized Exploratory Well Costs
	2017
	(in millions)
Balance at January 1,	$	14.2
Additions to capitalized exploratory well costs pending the determination of proved reserves	10.0
Balance at June 30,	$	24.2
Capitalized exploratory well costs that have been capitalized for a period of one year or less	$	10.4
Capitalized exploratory well costs that have been capitalized for a period greater than one year	13.8
Total capitalized exploratory well costs	$	24.2
Number of projects with exploratory well costs that have been capitalized for a period greater than one year	1