Accrued Liabilities and Other Long Term Liabilities (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Accrued Liabilities, Current [Abstract]
Compensation And Payroll Taxes	$ 10,120	$ 12,418
Accrued Expense	6,544	7,701
Accrued Pricing Adjustments	1,130	5,252
Equipment Purchases	5,412	3,191
Accrued professional services	1,423	1,483
Other	6,164	7,590
Accrued Liabilities, Current, Total	30,793	37,635
Liabilities, Noncurrent [Abstract]
Accrued defined benefit plan	13,493	24,863
Unrecognized tax benefits	10,177	9,173	8,064
Deferred compensation	1,932	2,734
Other	5,097	750
Liabilities, Noncurrent, Total	$ 30,699	$ 37,520