SEVERANCE, RESTRUCTURING AND RELATED CHARGES (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 25, 2015	Sep. 26, 2014	Sep. 25, 2015	Sep. 26, 2014
Restructuring Cost and Reserve [Line Items]
Total restructuring costs	$ 1,777	$ 0	$ 3,914	$ 0
Restructuring and Related Cost, Expected Cost [Abstract]
Estimated severance, restructuring and related charges	5,800		5,800
Restructuring Reserve [Roll Forward]
Restructuring liabilities at December 31, 2014			0
Additions			3,914
Payments			(3,060)
Other			0
Restructuring liabilities at September 25, 2015	854		854
Severance costs			600
Other relocation associated costs			3,600
Additional incentive payment received included in other liabilities			500
General and Administrative Expense [Member]
Restructuring and Related Cost, Expected Cost [Abstract]
Incentive payment received upon signing of lease	1,700		1,700
Restructuring Reserve [Roll Forward]
Recognized gain on liability from acceleration of lease term			700
City [Member]
Restructuring Reserve [Roll Forward]
Additional incentive payment received included in other liabilities			400
County [Member]
Restructuring Reserve [Roll Forward]
Additional incentive payment received included in other liabilities			100
Contract Termination Costs [Member]
Restructuring Cost and Reserve [Line Items]
Total restructuring costs	0		1,600
Restructuring Reserve [Roll Forward]
Restructuring liabilities at December 31, 2014			0
Additions			1,600
Payments			(1,600)
Other			0
Restructuring liabilities at September 25, 2015	0		0
Other Associated Costs [Member]
Restructuring Cost and Reserve [Line Items]
Total restructuring costs	1,226		1,663
Restructuring Reserve [Roll Forward]
Restructuring liabilities at December 31, 2014			0
Additions			1,663
Payments			(1,429)
Other			0
Restructuring liabilities at September 25, 2015	234		234
Severance Costs [Member]
Restructuring Cost and Reserve [Line Items]
Total restructuring costs	551		651
Restructuring Reserve [Roll Forward]
Restructuring liabilities at December 31, 2014			0
Additions			651
Payments			(31)
Other			0
Restructuring liabilities at September 25, 2015	$ 620		$ 620