Accounting for Derivative Instruments and Hedging Activities (Details) (USD $)
In Millions, unless otherwise specified |
3 Months Ended | 12 Months Ended | 3 Months Ended | 12 Months Ended | 3 Months Ended | 12 Months Ended | 3 Months Ended | 12 Months Ended | 3 Months Ended | 12 Months Ended | 3 Months Ended | |||||||||||||||||||||||||||
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Mar. 31, 2014
|
Dec. 31, 2013
|
Mar. 31, 2014
Derivatives Designated as Cash Flow Hedges
|
Dec. 31, 2013
Derivatives Designated as Cash Flow Hedges
|
Mar. 31, 2014
Derivatives Not Designated as Cash Flow Hedges
|
Dec. 31, 2013
Derivatives Not Designated as Cash Flow Hedges
|
Mar. 31, 2014
Interest rate contracts
|
Dec. 31, 2013
Interest rate contracts
|
Mar. 31, 2014
Interest rate contracts current
Derivatives Designated as Cash Flow Hedges
|
Dec. 31, 2013
Interest rate contracts current
Derivatives Designated as Cash Flow Hedges
|
Mar. 31, 2014
Interest rate contracts current
Derivatives Not Designated as Cash Flow Hedges
|
Dec. 31, 2013
Interest rate contracts current
Derivatives Not Designated as Cash Flow Hedges
|
Mar. 31, 2014
Interest rate contracts long-term
Derivatives Designated as Cash Flow Hedges
|
Dec. 31, 2013
Interest rate contracts long-term
Derivatives Designated as Cash Flow Hedges
|
Mar. 31, 2014
Interest rate contracts long-term
Derivatives Not Designated as Cash Flow Hedges
|
Dec. 31, 2013
Interest rate contracts long-term
Derivatives Not Designated as Cash Flow Hedges
|
Mar. 31, 2014
Commodity contracts current
Derivatives Designated as Cash Flow Hedges
|
Dec. 31, 2013
Commodity contracts current
Derivatives Designated as Cash Flow Hedges
|
Mar. 31, 2014
Commodity contracts current
Derivatives Not Designated as Cash Flow Hedges
|
Dec. 31, 2013
Commodity contracts current
Derivatives Not Designated as Cash Flow Hedges
|
Mar. 31, 2014
Commodity contracts long-term
Derivatives Designated as Cash Flow Hedges
|
Dec. 31, 2013
Commodity contracts long-term
Derivatives Designated as Cash Flow Hedges
|
Mar. 31, 2014
Commodity contracts long-term
Derivatives Not Designated as Cash Flow Hedges
|
Dec. 31, 2013
Commodity contracts long-term
Derivatives Not Designated as Cash Flow Hedges
|
Mar. 31, 2014
Short Ton
Emissions
T
|
Dec. 31, 2013
Short Ton
Emissions
T
|
Mar. 31, 2014
Short Ton
Coal
T
|
Dec. 31, 2013
Short Ton
Coal
T
|
Mar. 31, 2014
MMbtu
Natural Gas
|
Dec. 31, 2013
MMbtu
Natural Gas
|
Mar. 31, 2014
Barrel
Oil
bbl
|
Dec. 31, 2013
Barrel
Oil
bbl
|
Mar. 31, 2014
MWh
Power
|
Dec. 31, 2013
MWh
Power
|
Mar. 31, 2014
Dollars
Interest
|
Dec. 31, 2013
Dollars
Interest
|
Mar. 31, 2014
CVSR
Interest rate contracts
|
Mar. 31, 2013
Alpine
Interest rate contracts
|
|
Derivative | ||||||||||||||||||||||||||||||||||||||
Loss previously deferred in OCI recognized in earnings resulting from discontinued cash flow hedge accounting | ||||||||||||||||||||||||||||||||||||||
Volumetric Underlying Derivative Transactions | ||||||||||||||||||||||||||||||||||||||
Derivative, Nonmonetary Notional Amount, Volume | 1,000,000 | 1,000,000 | ||||||||||||||||||||||||||||||||||||
Derivative, Nonmonetary Notional Amount, Energy Measure | 111,000,000 | (166,000,000) | 35,000,000 | (27,000,000) | ||||||||||||||||||||||||||||||||||
Derivative, Nonmonetary Notional Amount, Mass | 2,000,000 | 0 | 50,000,000 | 51,000,000 | ||||||||||||||||||||||||||||||||||
Derivative, Notional Amount | 1,439 | 1,444 | ||||||||||||||||||||||||||||||||||||
Fair Value of Derivative Instrument | ||||||||||||||||||||||||||||||||||||||
Derivative Assets | 1,906 | 1,639 | 8 | 14 | 1,898 | 1,625 | 12 | 20 | 0 | 0 | 0 | 0 | 8 | 14 | 4 | 6 | 0 | 0 | 1,573 | 1,328 | 0 | 0 | 321 | 291 | ||||||||||||||
Derivative Liabilities | $ 1,761 | $ 1,250 | $ 63 | $ 66 | $ 1,698 | $ 1,184 | $ 70 | $ 69 | $ 32 | $ 35 | $ 5 | $ 4 | $ 31 | $ 29 | $ 2 | $ 1 | $ 0 | $ 1 | $ 1,467 | $ 1,015 | $ 0 | $ 1 | $ 224 | $ 164 |