FAIR VALUE MEASUREMENTS - Summary of fair value hierarchy for financial assets (cash equivalents and investments in marketable securities) measured at fair value on recurring basis - (Details) (Recurring basis, USD $) In Thousands, unless otherwise specified	Dec. 31, 2012		Dec. 31, 2011
Level 1 | Money market funds
Fair Value, Assets and Liabilities Measured On Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	$ 5,003	[1]	$ 9,237	[1]
Level 1 | Accrued contingent consideration
Fair Value, Assets and Liabilities Measured On Recurring and Nonrecurring Basis [Line Items]
Available for sale securities				[2]
Level 2 | Money market funds
Fair Value, Assets and Liabilities Measured On Recurring and Nonrecurring Basis [Line Items]
Available for sale securities		[1]		[1]
Level 2 | Accrued contingent consideration
Fair Value, Assets and Liabilities Measured On Recurring and Nonrecurring Basis [Line Items]
Available for sale securities				[2]
Level 3 | Money market funds
Fair Value, Assets and Liabilities Measured On Recurring and Nonrecurring Basis [Line Items]
Available for sale securities		[1]		[1]
Level 3 | Accrued contingent consideration
Fair Value, Assets and Liabilities Measured On Recurring and Nonrecurring Basis [Line Items]
Available for sale securities			4,626	[2]
Total | Money market funds
Fair Value, Assets and Liabilities Measured On Recurring and Nonrecurring Basis [Line Items]
Available for sale securities	5,003	[1]	9,237	[1]
Total | Accrued contingent consideration
Fair Value, Assets and Liabilities Measured On Recurring and Nonrecurring Basis [Line Items]
Available for sale securities			$ 4,626	[2]

[1] Included in "Cash and cash equivalents" in the consolidated balance sheets as of December 31, 2012 and 2011 in addition to $23.6 million and $20.6 million, respectively, of cash. Unrealized gains and losses on money market funds were nominal due to the short-term nature of the investments.

[2] The fair value of accrued contingent consideration was calculated by discounting the known settlement amount of $5.0 million using the borrowing rate from our credit facility.