Business Segments, Concentration of Business, and Credit Risk and Significant Customers (Details 3) (USD $) In Thousands, unless otherwise specified					3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2012	Dec. 31, 2011	Sep. 30, 2013 International Net Sales	Sep. 30, 2012 International Net Sales	Sep. 30, 2013 International Net Sales	Sep. 30, 2012 International Net Sales	Dec. 31, 2012 Net Trade Accounts Receivable Customer One customer	Sep. 30, 2013 US Long-lived assets	Dec. 31, 2012 US Long-lived assets	Sep. 30, 2013 All other countries Long-lived assets	Dec. 31, 2012 All other countries Long-lived assets
Cash and cash equivalents
Money market fund accounts	$ 35,167	$ 52,650
Cash	48,940	57,597
Total cash and cash equivalents	84,107	110,247	61,636	263,606
Long-lived assets, which consist of property and equipment, by major country
Property and equipment, by major country	$ 164,412	$ 125,370								$ 126,866	$ 89,423	$ 37,546	$ 35,947
Concentration risks
Number of customers considered concentration risk									1
Concentration risk (as a percent)									18.80%
Concentration risk benchmark (as a percent)					38.30%	35.60%	35.20%	34.00%