STOCK-BASED COMPENSATION PLANS - Summary of stock option activity (Details 1) (Stock Option, USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
Dec. 31, 2012
Stock Option
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Balance, December 31, 2011	4,643
Granted	1,632
Exercised	(516)
Forfeitures and post-vesting cancellations	(1,058)
Balance, December 31, 2012	4,701
Exercisable, December 31, 2012	2,532
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Roll Forward]
Balance, December 31, 2011	$ 6.13
Granted	$ 7.64
Exercised	$ 4.79
Forfeitures and post-vesting cancellations	$ 7.09
Balance, December 31, 2012	$ 6.57
Exercisable, December 31, 2012	$ 6.31

The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

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The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan.

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For presentations that combine terminations, the number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan or that expired.

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The number of shares reserved for issuance under stock option agreements awarded under the plan that validly exist and are outstanding as of the balance sheet date, including vested options.

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Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

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Weighted average price at which option holders acquired shares when converting their stock options into shares.

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Number of share options (or share units) exercised during the current period.

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