Summary of Significant Accounting Policies (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012 item	Dec. 31, 2011
Risk Concentration
Number of major U.S. financial institutions with whom cash, cash equivalents and investments are maintained	2
Number of suppliers from whom certain components may be available	1
Property and equipment
Depreciation and amortization	$ 155	$ 109
Equipment and furniture and fixtures | Minimum
Property and equipment
Estimated useful lives	1 year
Equipment and furniture and fixtures | Maximum
Property and equipment
Estimated useful lives	5 years
Leasehold improvements | Minimum
Property and equipment
Estimated useful lives	2 years
Leasehold improvements | Maximum
Property and equipment
Estimated useful lives	5 years