Income Taxes - Deferred Income Tax Assets (Liabilities) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Income Tax Disclosure [Abstract]
Accruals and reserves	$ 1,632	$ 2,271
Net operating loss carryforwards	7,067	14,816
Research and development credit carryforward	1,260	858
Other	73	0
Gross deferred tax asset	10,032	17,945
Valuation allowance	(10,032)	(17,945)
Net deferred tax asset	$ 0	$ 0