v3.19.3
Segment Information (Details) - USD ($)
$ in Millions
 3 Months Ended 9 Months Ended
Sep. 30, 2019
Sep. 30, 2018
Sep. 30, 2019
Sep. 30, 2018
Revenues from External Customers and Long-Lived Assets [Line Items]        
Total operating revenues(1) $ 2,792 [1] $ 2,890 [1] $ 7,990 [2] $ 7,158 [2]
Commodity Margin 1,127 974 2,658 2,280
Add: Mark-to-market commodity activity, net and other(2) 34 [3] 70 [3] 286 [4] (107) [4]
Operating and maintenance expense 255 248 739 765
Depreciation and amortization expense 173 179 522 566
General and other administrative expense 39 31 105 122
Other operating expenses 15 23 53 79
Impairment losses 0 0 55 0
(Income) loss from unconsolidated investments in power plants (3) (5) (14) (16)
Income from operations 682 568 1,484 657
Interest expense 153 158 459 466
Debt Extinguishment Costs and Other (Income) Expense, Net 17 4 44 73
Income before income taxes 512 406 981 118
Lease levelization 31 30 (4) (5)
West [Member]        
Revenues from External Customers and Long-Lived Assets [Line Items]        
Total operating revenues(1) 856 [1] 701 [1] 2,187 [2] 1,536 [2]
Commodity Margin 393 356 908 782
Add: Mark-to-market commodity activity, net and other(2) 110 [3] (13) [3] 224 [4] (23) [4]
Operating and maintenance expense 82 85 247 255
Depreciation and amortization expense 61 70 194 204
General and other administrative expense 10 7 22 28
Other operating expenses 9 11 25 33
Impairment losses     0  
(Income) loss from unconsolidated investments in power plants 0 0 0 0
Income from operations 341 170 644 239
Texas [Member]        
Revenues from External Customers and Long-Lived Assets [Line Items]        
Total operating revenues(1) 867 [1] 1,022 [1] 2,509 [2] 2,155 [2]
Commodity Margin 369 187 704 504
Add: Mark-to-market commodity activity, net and other(2) (107) [3] 137 [3] 177 [4] (109) [4]
Operating and maintenance expense 71 63 202 208
Depreciation and amortization expense 47 57 146 190
General and other administrative expense 13 12 40 50
Other operating expenses 2 3 5 22
Impairment losses     0  
(Income) loss from unconsolidated investments in power plants 0 0 0 0
Income from operations 129 189 488 (75)
East [Member]        
Revenues from External Customers and Long-Lived Assets [Line Items]        
Total operating revenues(1) 348 [1] 460 [1] 1,683 [2] 1,415 [2]
Commodity Margin 265 320 765 729
Add: Mark-to-market commodity activity, net and other(2) (69) [3] (26) [3] 38 [4] 7 [4]
Operating and maintenance expense 69 72 208 208
Depreciation and amortization expense 51 39 142 133
General and other administrative expense 12 7 31 30
Other operating expenses 4 9 23 24
Impairment losses     55  
(Income) loss from unconsolidated investments in power plants (3) (5) (15) (17)
Income from operations 63 172 359 358
Retail [Member]        
Revenues from External Customers and Long-Lived Assets [Line Items]        
Total operating revenues(1) 1,096 [1] 1,125 [1] 3,176 [2] 2,998 [2]
Commodity Margin 100 111 281 265
Add: Mark-to-market commodity activity, net and other(2) 108 [3] (20) [3] (127) [4] 41 [4]
Operating and maintenance expense 41 36 108 117
Depreciation and amortization expense 14 13 40 39
General and other administrative expense 4 5 12 14
Other operating expenses 0 0 0 0
Impairment losses     0  
(Income) loss from unconsolidated investments in power plants 0 0 1 1
Income from operations 149 37 (7) 135
Consolidation, Eliminations [Member]        
Revenues from External Customers and Long-Lived Assets [Line Items]        
Total operating revenues(1) (375) [1] (418) [1] (1,565) [2] (946) [2]
Commodity Margin 0 0 0 0
Add: Mark-to-market commodity activity, net and other(2) (8) [3] (8) [3] (26) [4] (23) [4]
Operating and maintenance expense (8) (8) (26) (23)
Depreciation and amortization expense 0 0 0 0
General and other administrative expense 0 0 0 0
Other operating expenses 0 0 0 0
Impairment losses     0  
(Income) loss from unconsolidated investments in power plants 0 0 0 0
Income from operations 0 0 0 0
Intersegment Eliminations [Member] | West [Member]        
Revenues from External Customers and Long-Lived Assets [Line Items]        
Total operating revenues(1) 133 160 395 344
Intersegment Eliminations [Member] | Texas [Member]        
Revenues from External Customers and Long-Lived Assets [Line Items]        
Total operating revenues(1) 225 238 784 447
Intersegment Eliminations [Member] | East [Member]        
Revenues from External Customers and Long-Lived Assets [Line Items]        
Total operating revenues(1) 13 19 378 152
Intersegment Eliminations [Member] | Retail [Member]        
Revenues from External Customers and Long-Lived Assets [Line Items]        
Total operating revenues(1) 4 1 8 3
Other Assets [Member]        
Revenues from External Customers and Long-Lived Assets [Line Items]        
Amortization of Intangible Assets $ 20 $ 26 $ 59 $ 79
[1] Includes intersegment revenues of $133 million and $160 million in the West, $225 million and $238 million in Texas, $13 million and $19 million in the East and $4 million and $1 million in Retail for the three months ended September 30, 2019 and 2018, respectively.
[2] Includes intersegment revenues of $395 million and $344 million in the West, $784 million and $447 million in Texas, $378 million and $152 million in the East and $8 million and $3 million in Retail for the nine months ended September 30, 2019 and 2018, respectively.
[3] Includes $31 million and $30 million of lease levelization and $20 million and $26 million of amortization expense for the three months ended September 30, 2019 and 2018, respectively.
[4] Includes $(4) million and $(5) million of lease levelization and $59 million and $79 million of amortization expense for the nine months ended September 30, 2019 and 2018, respectively.