CASH AND CASH EQUIVALENTS AND SHORT-TERM INVESTMENTS; BANK OVERDRAFT (Details) (USD $) In Thousands, unless otherwise specified					1 Months Ended			12 Months Ended		12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Jul. 31, 2012 Ruble-denominated deposits	Dec. 31, 2013 Ruble-denominated deposits	Dec. 31, 2012 Ruble-denominated deposits	Dec. 31, 2013 US dollar-denominated deposits	Dec. 31, 2012 US dollar-denominated deposits	Dec. 31, 2013 Low end of range	Dec. 31, 2013 Low end of range Ruble-denominated deposits	Dec. 31, 2012 Low end of range Ruble-denominated deposits	Dec. 31, 2013 High end of range	Dec. 31, 2013 High end of range Ruble-denominated deposits	Dec. 31, 2012 High end of range Ruble-denominated deposits
CASH, CASH EQUIVALENTS AND SHORT-TERM INVESTMENTS; BANK OVERDRAFT
Deposits in banks with original maturity period for classification as short-term investments										91 days			365 days
Bank accounts						$ 16,616	$ 23,519	$ 12,754	$ 31,021
Other	1,204	641
Total cash and cash equivalents	30,574	55,181	12,331	59,565
Short-term investments	180,337	131,449				178,937	131,449	1,400
Annual interest rate (as a percent)								0.27%			6.30%	7.65%		9.00%	9.25%
Credit limit under overdraft agreement					31,000
Overdraft position	$ 3,390	$ 13,181
Variable interest rate basis					Mosprime rate
Variable interest rate (as a percent)					2.21%