BASIS OF PRESENTATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details 4) (USD $) In Thousands, unless otherwise specified	9 Months Ended	12 Months Ended
	Sep. 30, 2011 Segment D Y Month step Count sqm	Dec. 31, 2010 D Count sqm
New Accounting Pronouncements
Minimum number of reporting units with zero or negative carrying amount of goodwill to qualify for amended provisions of goodwill impairment test (in counts)		1
Number of steps involved in process of goodwill impairment test	2
More-likely-than-not threshold defined as minimum likelihood percentage	50.00%
Cash and Cash Equivalents and Short-Term Investments
Maximum original maturity period for classification as cash and cash equivalents (in days)	90
Deposits in banks with original maturity period for classification as short-term investments, low end of the range (in days)	91
Deposits in banks with original maturity period for classification as short-term investments, high end of the range (in days)	365
Maximum maturity period of cash and cash equivalents (in days)	90	90
Cash and deposits in Russian banks, including subsidiaries of foreign banks	$ 53,157	$ 57,452
Maturity period of deposits in Russian bank, greater than (in days)	90	90
Deposits in Russian banks	75,314	117,457
Ruble-denominated deposits	60,314
Interest rate on ruble-denominated deposits, low end of range (as a percent)	3.65%
Interest rate on ruble-denominated deposits, high end of range (as a percent)	6.80%
US dollar-denominated deposits	$ 15,000
Interest rate on US dollar-denominated deposits (as a percent)	2.10%