v3.8.0.1
Basis of Presentation and Summary of Significant Accounting Policies (Details) - USD ($)
$ / shares in Units, $ in Millions
 3 Months Ended 9 Months Ended
Sep. 30, 2017
Sep. 30, 2016
Sep. 30, 2017
Sep. 30, 2016
Dec. 31, 2016
Accounting Policies [Line Items]          
Sale of Stock, Price Per Share $ 15.25   $ 15.25    
Sale of Stock, Consideration Received on Transaction $ 5,600        
Payments for Merger Related Costs 11   $ 11    
Goodwill, Beginning Balance     187    
Goodwill, Purchase Accounting Adjustments [1]     7    
Goodwill, Ending Balance 243   243    
Current 196   196   $ 173
Non-current 26   26   15
Total 222   222   188
Interest costs capitalized 7 $ 5 20 $ 14  
Transfer of Financial Assets Accounted for as Sales, Fair Value of Derecognized Assets 228   228   211
Continuing Involvement with Continued to be Recognized Transferred Financial Assets, Amount Outstanding 40   40   32
Trade Receivables Sold     1,600    
Cash Flows Between Transferor and Transferee, Proceeds from New Transfers     1,600    
Margin deposits and other prepaid expense 182   182   364
Derivative assets, current [2],[3] 206   206   221
Total current assets 2,388   2,388   2,851
Derivative Asset, Noncurrent [2],[3] 284   284   300
Total assets 16,792   16,792   17,493
Derivative Liability, Current [2],[3] 113   113   138
Other current liabilities 427   427   523
Total current liabilities 1,794   1,794   2,205
Long-term derivative liabilities [2],[3] 103   103   149
Total liabilities 13,469   13,469   14,154
Derivative instruments, net     (10) (154)  
Other assets     60 1  
Accounts payable and accrued expenses     95 53  
Net cash provided by operating activities     807 667  
Debt service          
Accounting Policies [Line Items]          
Current 22   22   11
Non-current 7   7   8
Total 29   29   19
Construction major maintenance          
Accounting Policies [Line Items]          
Current 25   25   45
Non-current 17   17   6
Total 42   42   51
Security project insurance          
Accounting Policies [Line Items]          
Current 145   145   114
Non-current 0   0   0
Total 145   145   114
Other          
Accounting Policies [Line Items]          
Current 4   4   3
Non-current 2   2   1
Total 6   $ 6   4
Geothermal Properties, Gross [Member] | Minimum [Member]          
Accounting Policies [Line Items]          
Property, plant and equipment, estimated useful lives     13 years    
Geothermal Properties, Gross [Member] | Maximum [Member]          
Accounting Policies [Line Items]          
Property, plant and equipment, estimated useful lives     58 years    
Property, Plant and Equipment, Other Types [Member] | Minimum [Member]          
Accounting Policies [Line Items]          
Property, plant and equipment, estimated useful lives     3 years    
Property, Plant and Equipment, Other Types [Member] | Maximum [Member]          
Accounting Policies [Line Items]          
Property, plant and equipment, estimated useful lives     46 years    
Building, Machinery and Equipment, Gross [Member] | Minimum [Member]          
Accounting Policies [Line Items]          
Property, plant and equipment, estimated useful lives     3 years    
Building, Machinery and Equipment, Gross [Member] | Maximum [Member]          
Accounting Policies [Line Items]          
Property, plant and equipment, estimated useful lives     46 years    
Texas [Member]          
Accounting Policies [Line Items]          
Goodwill, Beginning Balance     $ 31    
Goodwill, Ending Balance 32   32    
East [Member]          
Accounting Policies [Line Items]          
Goodwill, Beginning Balance     88    
Goodwill, Purchase Accounting Adjustments [1]     8    
Goodwill, Ending Balance 145   145    
West [Member]          
Accounting Policies [Line Items]          
Goodwill, Beginning Balance     68    
Goodwill, Ending Balance 66   66    
Calpine Solutions [Member] | Texas [Member]          
Accounting Policies [Line Items]          
Goodwill, Purchase Accounting Adjustments [1]     1    
Calpine Solutions [Member] | East [Member]          
Accounting Policies [Line Items]          
Goodwill, Purchase Accounting Adjustments     (9)    
Calpine Solutions [Member] | West [Member]          
Accounting Policies [Line Items]          
Goodwill, Purchase Accounting Adjustments [1]     (2)    
North American Power [Member]          
Accounting Policies [Line Items]          
Goodwill, Acquired During Period     49    
North American Power [Member] | Texas [Member]          
Accounting Policies [Line Items]          
Goodwill, Acquired During Period     0    
North American Power [Member] | East [Member]          
Accounting Policies [Line Items]          
Goodwill, Acquired During Period     49    
Goodwill, Purchase Accounting Adjustments     17    
North American Power [Member] | West [Member]          
Accounting Policies [Line Items]          
Goodwill, Acquired During Period     0    
Scenario, Previously Reported [Member]          
Accounting Policies [Line Items]          
Margin deposits and other prepaid expense         441
Derivative assets, current         1,725
Total current assets         4,432
Derivative Asset, Noncurrent         543
Total assets         19,317
Derivative Liability, Current         1,630
Other current liabilities         528
Total current liabilities         3,702
Long-term derivative liabilities         476
Total liabilities         15,978
Derivative instruments, net       (71)  
Other assets       (75)  
Accounts payable and accrued expenses       46  
Net cash provided by operating activities       667  
Restatement Adjustment [Member]          
Accounting Policies [Line Items]          
Margin deposits and other prepaid expense         (77)
Derivative assets, current         (1,504)
Total current assets         (1,581)
Derivative Asset, Noncurrent         (243)
Total assets         (1,824)
Derivative Liability, Current         (1,492)
Other current liabilities         (5)
Total current liabilities         (1,497)
Long-term derivative liabilities         (327)
Total liabilities         $ (1,824)
Derivative instruments, net       (83)  
Other assets       76  
Accounts payable and accrued expenses       7  
Net cash provided by operating activities       $ 0  
Revolving Credit Facility [Member]          
Accounting Policies [Line Items]          
Line of Credit Facility, Maximum Borrowing Capacity 1,790   1,790    
Amendment No. 6 [Member] | Revolving Credit Facility [Member]          
Accounting Policies [Line Items]          
Line of Credit Facility, Maximum Borrowing Capacity $ 1,470   $ 1,470    
[1] The purchase price allocation adjustment in the East segment represents adjustments of $17 million for North American Power and $(9) million for Calpine Solutions.
[2] At December 31, 2016, current and long-term derivative assets are shown net of collateral of $(29) million and $(3) million, respectively, and current and long-term derivative liabilities are shown net of collateral of $19 million and $85 million, respectively.
[3] At September 30, 2017 and December 31, 2016, we had $115 million and $262 million of collateral under master netting arrangements that were not offset against our derivative instruments on the Consolidated Condensed Balance Sheets.