Business Segments, Concentration of Business, and Credit Risk and Significant Customers (Details 3) (USD $) In Thousands, unless otherwise specified					3 Months Ended		12 Months Ended
	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2012	Dec. 31, 2011	Mar. 31, 2013 International Net Sales	Mar. 31, 2012 International Net Sales	Dec. 31, 2012 Net Trade Accounts Receivable Customer One customer	Mar. 31, 2013 US Long-lived assets	Dec. 31, 2012 US Long-lived assets	Mar. 31, 2013 All other countries Long-lived assets	Dec. 31, 2012 All other countries Long-lived assets
Cash and cash equivalents
Money market fund accounts	$ 25,455	$ 52,650
Cash	39,136	57,597
Total cash and cash equivalents	64,591	110,247	228,571	263,606
Long-lived assets, which consist of property and equipment, by major country
Property and equipment, by major country	$ 129,836	$ 125,370						$ 96,284	$ 89,423	$ 33,552	$ 35,947
Concentration risks
Number of customers considered concentration risk							1
Concentration risk (as a percent)							18.80%
Concentration risk benchmark (as a percent)					30.70%	30.80%