Fair Value Measurements (Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	$ 84,665	$ 64,793
Total Assets	84,665	64,793
IDSI acquisition short-term note		(945)
Total current maturities of other long-term debt		(945)
Total Liabilities		(945)
Domestic money market funds [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	58,620	42,273
Non domestic bank certificates of deposit [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	26,045	22,520
Fair Value, Inputs, Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	84,665	64,793
Total Assets	84,665	64,793
Fair Value, Inputs, Level 1 [Member] | Domestic money market funds [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	58,620	42,273
Fair Value, Inputs, Level 1 [Member] | Non domestic bank certificates of deposit [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	26,045	22,520
Fair Value, Inputs, Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
IDSI acquisition short-term note		(945)
Total current maturities of other long-term debt		(945)
Total Liabilities		$ (945)