Consolidated Statements of Operations (USD $) In Millions, except Share data in Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Operating revenues:
Commodity revenue	$ 1,539	$ 1,177	$ 2,847	$ 2,389
Unrealized mark-to-market gain (loss)	31	(302)	(40)	(280)
Other revenue	2	4	6	6
Operating revenues	1,572	879	2,813	2,115
Operating expenses:
Commodity expense	998	570	1,833	1,261
Unrealized mark-to-market (gain) loss	2	44	(12)	(12)
Fuel and purchased energy expense	1,000	614	1,821	1,249
Plant operating expense	257	271	484	492
Depreciation and amortization expense	145	138	291	278
Sales, general and other administrative expense	36	35	69	68
Other operating expenses	20	19	38	40
Total operating expenses	1,458	1,077	2,703	2,127
(Income) from unconsolidated investments in power plants	(8)	(5)	(16)	(14)
Income (loss) from operations	122	(193)	126	2
Interest expense	170	184	346	369
Loss on interest rate derivatives	0	0	0	14
Interest (income)	(1)	(2)	(3)	(5)
Debt extinguishment costs	68	0	68	12
Other (income) expense, net	3	6	8	8
Income (loss) before income taxes	(118)	(381)	(293)	(396)
Income tax benefit	(48)	(52)	(98)	(58)
Net loss	(70)	(329)	(195)	(338)
Net income attributable to the noncontrolling interest	0	0	0	0
Net loss attributable to Calpine	$ (70)	$ (329)	$ (195)	$ (338)
Basic and diluted loss per common share attributable to Calpine:
Weighted average shares of common stock outstanding (in thousands)	447,558	471,444	449,620	474,775
Net loss per common share attributable to Calpine — basic and diluted	$ (0.16)	$ (0.69)	$ (0.43)	$ (0.71)