STOCK-BASED COMPENSATION PLANS (Details)	12 Months Ended
	Dec. 31, 2015 USD ($) item $ / shares shares	Dec. 31, 2014 USD ($) $ / shares shares	Dec. 31, 2013 USD ($) $ / shares shares	Dec. 31, 2012 $ / shares shares
STOCK-BASED COMPENSATION PLANS
Recognized employee stock-based compensation expense | $	$ 5,000,000	$ 3,100,000	$ 3,400,000
Employee Stock Purchase Plan
STOCK-BASED COMPENSATION PLANS
Shares available under the plan	1,200,000
Shares available for grant	1,027,086
Weighted-Average Grant Date Fair Value
Offering period for the plan	3 months
Period of interval between occurrence of purchases	3 months
IRS regulated cap for payroll deduction to purchase common stock | $	$ 25,000
Purchase price expressed as a percentage of fair market value of common stock (as a percent)	90.00%
Shares issued under ESPP	159,335
Shares available for purchase under ESPP	1,027,086
Minimum | Employee Stock Purchase Plan
Weighted-Average Grant Date Fair Value
Eligible service period of employees per week to participate in the plan	20 hours
Eligible service period of employees in a calendar year to participate in the plan	5 months
Percentage of employees' eligible earnings as payroll deduction to purchase common stock	1.00%
Maximum | Employee Stock Purchase Plan
Weighted-Average Grant Date Fair Value
Percentage of employees' eligible earnings as payroll deduction to purchase common stock	10.00%
Equity Incentive Plan2007
STOCK-BASED COMPENSATION PLANS
Shares available for grant	3,388,143
Weighted-Average Grant Date Fair Value
Total fair value RSUs vested (in dollars) | $	$ 3,600,000	$ 1,400,000	$ 3,800,000
Equity Incentive Plan2007 | Maximum
STOCK-BASED COMPENSATION PLANS
Anniversary period from the grant date on which the award will expire	10 years
Equity Incentive Plan2007 | Stock Appreciation Rights S A R S
STOCK-BASED COMPENSATION PLANS
Number of anniversaries | item	4
Anniversary period from the grant date on which the award will expire	10 years
Period following the employee's termination of services as a result of death or permanent disability after which the award will expire	1 year
Period following fourth anniversary from the grant date after which the award will expire	90 days
Period following the participant's termination of employment due to reasons other than death, disability or retirement after which the award will expire	30 days
SARs
Outstanding at the beginning of the period (in shares)	106,000	132,000	265,000
Exercised (in shares)	(25,000)	(13,000)	(45,000)
Forfeited (in shares)	(34,000)	(13,000)	(88,000)
Outstanding at the end of the period (in shares)	47,000	106,000	132,000	265,000
Vested and expected to vest at the end of the period (in shares)	47,000
Exercisable at the end of the period (in shares)	47,000
Weighted-Average Exercise Price
Outstanding at the beginning of the period (in dollars per share) | $ / shares	$ 5.78	$ 5.28	$ 4.92
Exercised (in dollars per share) | $ / shares	3.17	3.18	3.18
Forfeited (in dollars per share) | $ / shares	7.20	3.18	5.27
Outstanding at the end of the period (in dollars per share) | $ / shares	6.13	$ 5.78	$ 5.28	$ 4.92
Vested and expected to vest at the end of the period (in dollars per share) | $ / shares	6.13
Exercisable at the end of the period (in dollars per share) | $ / shares	$ 6.13
Weighted-Average Remaining Contractual Life
Outstanding at the end of the period	2 years 2 months 12 days	3 years 3 months 18 days	4 years 4 months 24 days	5 years 6 months
Vested and expected to vest at the end of the period	2 years 2 months 12 days
Exercisable at the end of the period	2 years 2 months 12 days
Aggregate Intrinsic Value
Outstanding at the beginning of the period (in dollars) | $	$ 39,000	$ 67,000
Exercised (in dollars) | $	32,000	22,000	$ 45,000
Forfeited (in dollars) | $		(22,000)
Outstanding at the end of the period (in dollars) | $	6,000	39,000	67,000
Vested and expected to vest at the end of the period (in dollars) | $	6,000
Exercisable at the end of the period (in dollars) | $	6,000
Total fair value of the awards vested | $	$ 0	$ 0	$ 6,000
Equity Incentive Plan2007 | Stock Appreciation Rights S A R S | Awards Vesting On Four Anniversaries
STOCK-BASED COMPENSATION PLANS
Award vesting percentage	25.00%
Equity Incentive Plan2007 | Restricted Stock Units R S U
Aggregate Intrinsic Value
Percentage of relevant period has elapsed for prorata vesting of the awards	50.00%
RSA and RSU
Non-vested at the beginning of the period (in shares)	2,636,000	1,627,000	2,348,000
Granted (in shares)	1,881,000	1,729,000	1,578,000
Vested (in shares)	(1,099,000)	(689,000)	(2,045,000)
Forfeited (in shares)	(250,000)	(31,000)	(254,000)
Non-vested at the end of the period (in shares)	3,168,000	2,636,000	1,627,000	2,348,000
Weighted-Average Grant Date Fair Value
Non-vested at the beginning of the period (in dollars per share) | $ / shares	$ 3.73	$ 2.13	$ 1.71
Granted (in dollars per share) | $ / shares	3.90	4.56	2.31
Vested (in dollars per share) | $ / shares	3.29	2.03	1.85
Forfeited (in dollars per share) | $ / shares	3.28	3.23	1.68
Non-vested at the end of the period (in dollars per share) | $ / shares	$ 4.02	$ 3.73	$ 2.13	$ 1.71
Unrecognized compensation cost related to the RSUs | $	$ 7,400,000
Weighted-average period to recognize unrecognized compensation cost	2 years 3 months 18 days
Equity Incentive Plan2007 | Restricted Stock Units R S U | Awards Vesting On Employment Through The Fourth Anniversary Of Grant
STOCK-BASED COMPENSATION PLANS
Award vesting percentage	100.00%
Equity Incentive Plan2007 | Restricted Stock | Awards Vesting On Change In Control
STOCK-BASED COMPENSATION PLANS
Award vesting percentage	100.00%