CASH AND CASH EQUIVALENTS AND SHORT-TERM INVESTMENTS; BANK OVERDRAFT (Details) (USD $) In Thousands, unless otherwise specified	1 Months Ended										12 Months Ended
	Jul. 31, 2012	Oct. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2012 Ruble-denominated deposits	Dec. 31, 2011 Ruble-denominated deposits	Dec. 31, 2012 US dollar-denominated deposits	Dec. 31, 2011 US dollar-denominated deposits	Dec. 31, 2012 Low end of range	Dec. 31, 2012 Low end of range Ruble-denominated deposits	Dec. 31, 2011 Low end of range Ruble-denominated deposits	Dec. 31, 2011 Low end of range US dollar-denominated deposits	Dec. 31, 2012 High end of range	Dec. 31, 2012 High end of range Ruble-denominated deposits	Dec. 31, 2011 High end of range Ruble-denominated deposits	Dec. 31, 2011 High end of range US dollar-denominated deposits
CASH, CASH EQUIVALENTS AND SHORT-TERM INVESTMENTS
Deposits in banks with original maturity period for classification as short-term investments											91 days				365 days
Bank accounts							$ 23,519	$ 6,434	$ 31,021	$ 4,479
Other			641	1,418
Total cash and cash equivalents			55,181	12,331	59,565	84,441
Short-term investments			131,449	117,233			131,449	102,068		15,165
Annual interest rate (as a percent)												7.65%	4.10%	2.10%		9.25%	8.70%	2.20%
Annual interest (as a percent)		7.20%
Credit limit under overdraft agreement	32,000	34,000
Overdraft position			$ 13,181	$ 16,941
Variable interest rate basis	Mosprime rate
Variable interest rate (as a percent)	2.21%