Summary of Significant Accounting Policies Estimated future amortization expense related to intangible assets (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Expected Amortization Expense [Line Items]
Finite-Lived Intangible Assets, Amortization Expense, Remainder of Fiscal Year	$ 68
Finite-Lived Intangible Assets, Amortization Expense, Year Two	60
Finite-Lived Intangible Assets, Amortization Expense, Year Three	36
Finite-Lived Intangible Assets, Amortization Expense, Year Four	22
Finite-Lived Intangible Assets, Amortization Expense, Year Five	19
Finite-Lived Intangible Assets, Amortization Expense, after Year Five	34
Finite-Lived Intangible Assets, Net	239
Patents [Member]
Expected Amortization Expense [Line Items]
Finite-Lived Intangible Assets, Net	$ 111	$ 137