v3.3.1.900
Capital Structure (Details) - USD ($)
$ / shares in Units, $ in Millions
 12 Months Ended
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Class of Stock [Line Items]        
Common Stock, authorized shares (in shares) 1,400,000,000 1,400,000,000    
Common Stock, issued shares (in shares) 356,755,747 502,287,022    
Common Stock, par value (in dollars per share) $ 0.001 $ 0.001    
Common Stock, outstanding shares (in shares) 356,662,004 381,921,264 429,038,988 457,048,970
Shares issued under Calpine Equity Incentive Plans 1,341,908 2,566,799 3,022,128  
Share repurchase program (26,601,168) (49,684,523) (31,032,110)  
Treasury Stock, Shares, Retired 0      
Treasury Stock, Shares (in shares) 93,743 120,365,758    
Treasury Stock, Value $ 1 $ 2,345    
Payments for Repurchase of Common Stock $ 529 $ 1,100 $ 623  
Treasury Stock Acquired, Average Cost Per Share $ 19.87      
Shares Issued [Member]        
Class of Stock [Line Items]        
Common Stock, issued shares (in shares) 356,755,747 502,287,022 497,841,056 492,495,100
Shares issued under Calpine Equity Incentive Plans 2,431,236 4,445,966 5,345,956  
Share repurchase program 0 0 0  
Treasury Stock, Shares, Retired 147,962,511      
Treasury Stock [Member]        
Class of Stock [Line Items]        
Shares issued under Calpine Equity Incentive Plans (1,089,328) (1,879,167) (2,323,828)  
Share repurchase program (26,601,168) (49,684,523) (31,032,110)  
Treasury Stock, Shares, Retired 147,962,511      
Treasury Stock, Shares (in shares) 93,743 120,365,758 68,802,068 35,446,130