Financial and Other Derivative Instruments (Tables)
 9 Months Ended
Sep. 30, 2012
Derivative Instruments and Hedging Activities Disclosure [Abstract]  
Fair value of derivative instruments
The following tables present the fair value of derivative instruments as of September 30, 2012 and December 31, 2011 (in millions):
 
September 30, 2012
 
December 31, 2011
 
Derivative Assets
 
Derivative Liabilities
 
Derivative Assets
 
Derivative Liabilities
Derivatives designated as hedging instruments:
 
 
 
 
 
 
 
Interest rate contracts
$
—

 
$
(1
)
 
$
—

 
$
(1
)
Derivatives not designated as hedging instruments:
 
 
 
 
 
 
 
Foreign currency exchange contracts
$
1

 
$
(2
)
 
$
3

 
$
(5
)
Commodity Contracts:
 
 
 
 
 

 
 

Natural Gas
959

 
(975
)
 
2,024

 
(2,080
)
Electricity
431

 
(419
)
 
747

 
(705
)
Other
53

 
(38
)
 
31

 
(20
)
Total derivatives not designated as hedging instruments:
$
1,444

 
$
(1,434
)
 
$
2,805

 
$
(2,810
)
Total derivatives:
 
 
 
 
 
 
 
Current
$
1,161

 
$
(1,185
)
 
$
2,272

 
$
(2,282
)
Noncurrent
283

 
(250
)
 
533

 
(529
)
Total derivatives
$
1,444

 
$
(1,435
)
 
$
2,805

 
$
(2,811
)

 
September 30, 2012
 
December 31, 2011
 
Derivative Assets
 
Derivative Liabilities
 
Derivative Assets
 
Derivative Liabilities
 
Current
 
Noncurrent
 
Current
 
Noncurrent
 
Current
 
Noncurrent
 
Current
 
Noncurrent
Reconciliation of derivative instruments to Consolidated Statements of Financial Position:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Total fair value of derivatives
$
1,161

 
$
283

 
$
(1,185
)
 
$
(250
)
 
$
2,272

 
$
533

 
$
(2,282
)
 
$
(529
)
Counterparty netting
(1,038
)
 
(220
)
 
1,038

 
220

 
(2,050
)
 
(440
)
 
2,050

 
440

Collateral adjustment
—

 
—

 
1

 
—

 
—

 
(19
)
 
74

 
—

Total derivatives as reported
$
123

 
$
63

 
$
(146
)
 
$
(30
)
 
$
222

 
$
74

 
$
(158
)
 
$
(89
)
Gain (Loss) Recognized in Income on Derivative
The effect of derivatives not designated as hedging instruments on the Consolidated Statements of Operations for the three and nine months ended September 30, 2012 and September 30, 2011 is as follows (in millions):
 
 
Location of Gain
(Loss) Recognized
in Income on Derivatives
 
Gain (Loss)
Recognized in
Income on
Derivatives for
the Three Months Ended
September 30
 
Gain (Loss)
Recognized in
Income on
Derivatives for
the Nine Months Ended
September 30
Derivatives not Designated as Hedging Instruments
 
 
2012
 
2011
 
2012
 
2011
Foreign currency exchange contracts
 
Operating Revenue
 
$
(2
)
 
$
4

 
$
(1
)
 
$
(1
)
Commodity Contracts:
 
 
 
 
 
 
 
 
 
 
Natural Gas
 
Operating Revenue
 
(54
)
 
9

 
(51
)
 
24

Natural Gas
 
Fuel, purchased power and gas
 
50

 
10

 
45

 
—

Electricity
 
Operating Revenue
 
17

 
35

 
52

 
64

Other
 
Operating Revenue
 
1

 
1

 
12

 
9

Total
 
 
 
$
12

 
$
59

 
$
57

 
$
96
Volume of Commodity Contracts [Table Text Block]
Commodity
 
Number of Units
Natural Gas (MMBtu)
 
574,807,803
Electricity (MWh)
 
37,735,336
Foreign Currency Exchange ($ CAD)
 
17,661,047