Quarterly Financial Data (unaudited) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended												12 Months Ended
	Mar. 31, 2013		Dec. 31, 2012		Sep. 30, 2012		Jun. 30, 2012		Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2011
Quarterly Financial Information Disclosure [Abstract]
Revenue	$ 28,515		$ 24,948		$ 22,491		$ 23,223		$ 24,600	$ 22,211	$ 21,852	$ 22,408	$ 99,177	$ 91,071	$ 97,088
Loss from operations	(1,380)		(1,769)		(18,418)		(644)		(4,797)	(974)	(383)	246	(22,211)	(5,908)	(2,603)
Net loss attributable to Rentrak Corporation	$ (2,028)		$ (1,814)		$ (18,157)		$ (618)		$ (4,617)	$ (1,947)	$ (261)	$ 399	$ (22,617)	$ (6,426)	$ (767)
Net income (loss) per share attributable to Rentrak Corporation:
Basic (per share)	$ (0.17)	[1]	$ (0.15)	[1]	$ (1.56)	[1]	$ (0.06)	[1]	$ (0.41)	$ (0.18)	$ (0.02)	$ 0.04	$ (1.93)	$ (0.57)	$ (0.07)
Diluted (per share)	$ (0.17)	[1]	$ (0.15)	[1]	$ (1.56)	[1]	$ (0.06)	[1]	$ (0.41)	$ (0.18)	$ (0.02)	$ 0.03	$ (1.93)	$ (0.57)	$ (0.07)

[1] Quarterly amounts presented may not add to year to date totals due to rounding.