Capitalized Exploratory Well Costs and Undeveloped Leasehold Costs (Tables)

3 Months Ended

Mar. 31, 2017

Changes in capitalized exploratory well costs are as follows and exclude amounts that were capitalized and subsequently expensed in the same period:



(millions)	Three Months Ended March 31, 2017
Capitalized Exploratory Well Costs, Beginning of Period	$	768
Additions to Capitalized Exploratory Well Costs Pending Determination of Proved Reserves	6
Reclassified to Proved Oil and Gas Properties Based on Determination of Proved Reserves ⁽¹⁾	(203		)
Capitalized Exploratory Well Costs, End of Period	$	571


⁽¹⁾	Amount relates to the approval and sanction of the first phase of development of the Leviathan field offshore Israel.

The following table provides an aging of capitalized exploratory well costs based on the date that drilling commenced:



(millions)	March 31, 2017		December 31, 2016
Exploratory Well Costs Capitalized for a Period of One Year or Less	$	58	$	69
Exploratory Well Costs Capitalized for a Period Greater Than One Year Since Commencement of Drilling ⁽¹⁾	513		699
Balance at End of Period	$	571	$	768