DEI Document	6 Months Ended
	Jun. 30, 2012	Aug. 15, 2012 Common Class A [Member]	Aug. 15, 2012 Common Class B [Member]
Entity Information [Line Items]
Entity registrant name	KAYAK Software Corp
Trading symbol	KYAK
Entity central index key	0001312928
Current fiscal year end date	--12-31
Entity filer category	Non-accelerated Filer
Document type	10-Q
Document period end date	Jun. 30, 2012
Document fiscal year focus	2012
Document fiscal period focus	Q2
Amendment flag	false
Entity common stock, shares outstanding		4,577,170	33,937,749