Restructuring Charges (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Restructuring Charges
Restructuring charges	$ 3,634,000	$ 696,000	$ 840,000
Changes in the restructuring accrual
Balance of restructuring accrual at the beginning of the period	1,050,000	1,340,000	1,234,000
Restructuring charges	3,630,000	669,000	788,000
Reversal of deferred rent related to facilities exited		60,000	29,000
Cash payments	(1,542,000)	(1,046,000)	(763,000)
Accretion of prior restructuring costs	4,000	27,000	52,000
Balance of restructuring accrual at the end of the period	3,142,000	1,050,000	1,340,000
Restructuring accrual included in other long-term liabilities	2,600,000
Facility Exit Costs
Changes in the restructuring accrual
Balance of restructuring accrual at the beginning of the period	448,000	1,340,000	1,234,000
Restructuring charges	76,000	67,000	788,000
Reversal of deferred rent related to facilities exited		60,000	29,000
Cash payments	(524,000)	(1,046,000)	(763,000)
Accretion of prior restructuring costs	4,000	27,000	52,000
Balance of restructuring accrual at the end of the period	4,000	448,000	1,340,000
Severance and Benefits
Changes in the restructuring accrual
Balance of restructuring accrual at the beginning of the period	602,000
Restructuring charges	3,554,000	602,000
Cash payments	(1,018,000)
Balance of restructuring accrual at the end of the period	$ 3,138,000	$ 602,000