Acquisitions and Divestitures (Tables)
 3 Months Ended
Mar. 31, 2015
Business Combinations [Abstract]  
Summary of operating results of discontinued operations
Summarized operating results of our discontinued operations were as follows:
 
Quarter ended March 31, 2014
 
(in millions)
Operating revenues
$
31

 
 
Operating expenses
 

Transportation costs
3

Lease operating expense
13

Depreciation, depletion and amortization
6

Impairment charges(1)
3

Other expense
5

Total operating expenses
30

 
 
Gain on sale of assets
13

Other income
3

Income from discontinued operations before income taxes
17

Income tax expense
7

Income from discontinued operations, net of tax
$
10

 
(1)                              During the quarter ended March 31, 2014, we recorded $3 million in impairment charges related to the sale of our Brazilian operations.