Accrued Liabilities and Other Long Term Liabilities (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Accrued Liabilities, Current [Abstract]
Compensation And Payroll Taxes	$ 12,837	$ 10,120
Accrued Expense	12,338	6,544
Accrued Pricing Adjustments	1,304	1,130
Equipment Purchases	7,081	5,412
Accrued professional services	2,512	1,423
Other	5,067	6,164
Accrued Liabilities, Current, Total	41,139	30,793
Liabilities, Noncurrent [Abstract]
Accrued defined benefit plan	17,853	13,493
Unrecognized tax benefits	14,591	10,177	9,173
Deferred compensation	2,213	1,932
Other	6,528	5,097
Liabilities, Noncurrent, Total	$ 41,185	$ 30,699