Restructuring Charges (Details) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Restructuring Charges
Restructuring charges	$ 696,000	$ 840,000	$ 130,000
Components of the restructuring charges and the payments and non-cash charges made against the accrual
Balance of restructuring accrual at the beginning of the period	1,340,000	1,234,000	1,876,000
Restructuring charges (benefit)	669,000	788,000	56,000
Reversal of deferred rent related to facilities exited	60,000	29,000
Cash payments	(1,046,000)	(763,000)	(772,000)
Accretion of prior restructuring costs	27,000	52,000	74,000
Balance of restructuring accrual at the end of the period	1,050,000	1,340,000	1,234,000
Restructuring accrual included in accrued liabilities	1,100,000
Facility Exit Costs
Components of the restructuring charges and the payments and non-cash charges made against the accrual
Balance of restructuring accrual at the beginning of the period	1,340,000	1,234,000	1,735,000
Restructuring charges (benefit)	67,000	788,000	60,000
Reversal of deferred rent related to facilities exited	60,000	29,000
Cash payments	(1,046,000)	(763,000)	(635,000)
Accretion of prior restructuring costs	27,000	52,000	74,000
Balance of restructuring accrual at the end of the period	448,000	1,340,000	1,234,000
Estimated sub-lease income	400,000
Acccrued facility exit cost estimated at fair value	400,000
Severance and Benefits
Components of the restructuring charges and the payments and non-cash charges made against the accrual
Balance of restructuring accrual at the beginning of the period			141,000
Restructuring charges (benefit)	602,000		(4,000)
Cash payments			(137,000)
Balance of restructuring accrual at the end of the period	$ 602,000