Document and Company Information	6 Months Ended
	Jun. 30, 2011	Jul. 26, 2011
Document and Company Information
Entity Registrant Name	Calpine Corp.
Entity Central Index Key	0000916457
Entity Currrent Reporting Status	Yes
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Well Known Seasoned Issuer	Yes
Document Fiscal Year Focus	2011
Document Fiscal Period Focus	Q2
Document Type	10-Q
Document Period End Date	Jun. 30, 2011
Amendment Flag	false
Entity Common Stock Shares Outstanding		459,500,298
Entity Voluntary Filers	No