COMMITMENTS AND CONTINGENCIES (Details) (USD $)	12 Months Ended			36 Months Ended
	Dec. 31, 2013 Y	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2013
Future minimum lease commitments under non-cancelable leases [Abstract]
2012	$ 20,183,000			$ 20,183,000
2013	13,462,000			13,462,000
2014	12,503,000			12,503,000
2015	11,301,000			11,301,000
2016	9,126,000			9,126,000
Thereafter	18,500,000			18,500,000
Total	85,075,000			85,075,000
Operating Lease Commitments [Abstract]
Rent expense under operating leases, net of operating subleases	16,300,000	18,100,000	20,200,000
Operating Leases, Income Statement, Sublease Revenue				0
Contingencies [Abstract]
ProductWarrantyAccrualAllocationToDivestitures		(507,000)
Purchase Commitments [Abstract]
Maximum purchase commitment period (in years)	1
Aggregate total of non-cancelable purchase commitments	27,600,000			27,600,000
Product warranty accrual [Roll Forward]
Accrual balance at beginning of year	4,476,000	5,100,000	4,849,000	4,849,000
Accruals for product warranties	5,346,000	7,737,000	8,544,000
Cost of warranty claims	(6,321,000)	(7,854,000)	(8,293,000)
Accrual balance at end of period	3,501,000	4,476,000	5,100,000	3,501,000
Operating Leases on Vacated Facilities [Member]
Operating Lease Commitments [Abstract]
Aggregate obligation of vacated facilies	(10,300,000)
Restructuring accruals related to operating leases on vacated space	(6,100,000)
Early termination penalties if options exercised	700,000			700,000
Standby Letters of Credit [Member]
Operating Lease Commitments [Abstract]
Letters of Credit Outstanding, Amount	2,400,000			2,400,000
Standby Letters of Credit [Member] | Office Space - Burlington, Massachusetts [Member]
Operating Lease Commitments [Abstract]
Number of renewal options on corporate office space in Burlington, Massachusetts	2			2
Maximum exposure	2,600,000			2,600,000
Minimum exposure	1,200,000			1,200,000
Standby Letters of Credit [Member] | Office Space - Daly City, California [Member]
Operating Lease Commitments [Abstract]
Maximum exposure	800,000			800,000
Opengate Litigation [Member]
Contingencies [Abstract]
Amount assessed and paid related to social taxes on stock-based compensation	1,700,000			1,700,000
Income Tax Examination, Liability (Refund) Adjustment from Settlement with Taxing Authority	$ 1,900,000			$ 1,900,000