COMMITMENTS AND CONTINGENCIES (Details) (USD $)	12 Months Ended
	Dec. 31, 2011 Y	Dec. 31, 2010	Dec. 31, 2009
Future minimum lease commitments under non-cancelable leases [Abstract]
2012	$ 22,312,000
2013	19,749,000
2014	17,005,000
2015	12,096,000
2016	12,143,000
Thereafter	35,866,000
Total	119,171,000
Operating Lease Commitments [Abstract]
Rent expense under operating leases, net of operating subleases	20,000,000	20,200,000	20,500,000
Rent received from operating subleases		1,100,000	1,800,000
Purchase Commitments [Abstract]
Maximum purchase commitment period (in years)	1
Aggregate total of non-cancelable purchase commitments	58,300,000
Product warranty accrual [Roll Forward]
Accrual balance at beginning of year	4,492,000	4,454,000
Acquired product warranty		339,000
Accruals for product warranties	7,023,000	5,046,000
Cost of warranty claims	(6,094,000)	(5,347,000)
Accrual balance at end of period	5,421,000	4,492,000	4,454,000
Product warranty information [Abstract]
Standard warranty period	90 days to one year
Extended warranty period	five
Operating Leases on Vacated Facilities [Member]
Operating Lease Commitments [Abstract]
Aggregate obligation of vacated facilies	(9,900,000)
Restructuring accruals related to operating leases on vacated space	(6,900,000)
Early termination penalties if options exercised	900,000
Standby Letters of Credit [Member]
Operating Lease Commitments [Abstract]
Letters of Credit Outstanding, Amount	3,600,000
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
Maximum exposure	2,600,000
Aggregate annual reductions to letters of credit at end of years two, three and five of the lease	400,000
Minimum exposure	1,300,000
Standby Letters of Credit [Member] | Office Space - Daly City, California [Member]
Operating Lease Commitments [Abstract]
Maximum exposure	800,000
Third Party Lease Financing [Member]
Operating Lease Commitments [Abstract]
Maximum exposure	400,000	1,000,000
Transactions with Recourse [Abstract]
Accruals for estimated losses	100,000	500,000
Opengate Litigation [Member]
Contingencies [Abstract]
Amount sought in litigation (in euros)	2,700,000
Engelke Litigation [Member]
Contingencies [Abstract]
Amount sought in litigation	15,000,000
Gain (Loss) Related to Litigation Settlement	5,600,000
Opengate Litigation [Member]
Contingencies [Abstract]
Amount assessed and paid related to social taxes on stock-based compensation	$ 1,700,000