Business Segments, Concentration of Business, and Credit Risk and Significant Customers (Details 3) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Long-lived assets, which consist of property and equipment, by major country
Property and equipment, by major country	90,257	47,737
Minimum
Concentration risks
Concentration risk (as a percent)	10.00%	10.00%	10.00%
International Net Sales
Concentration risks
Concentration risk benchmark (as a percent)	31.40%	23.70%	20.60%
Long-lived assets | Minimum
Concentration risks
Concentration risk (as a percent)	10.00%	10.00%
Net sales | Customer One
Concentration risks
Number of customers considered concentration risk		1	1
Concentration risk (as a percent)		11.90%	13.20%
Net Trade Accounts Receivable | Customer One
Concentration risks
Number of customers considered concentration risk	1	1
Concentration risk (as a percent)	17.10%	33.20%
Net Trade Accounts Receivable | Customer Two
Concentration risks
Concentration risk (as a percent)		10.10%
US | Long-lived assets
Long-lived assets, which consist of property and equipment, by major country
Property and equipment, by major country	65,034	36,591
UK | Long-lived assets
Long-lived assets, which consist of property and equipment, by major country
Property and equipment, by major country	6,703	6,753
All other countries | Long-lived assets
Long-lived assets, which consist of property and equipment, by major country
Property and equipment, by major country	18,520	4,393