Stock-Based Compensation - Summary of Option and RSU Activity (Details) - $ / shares			1 Months Ended		12 Months Ended
	Jan. 01, 2017	Aug. 23, 2016	May 31, 2015	Jun. 30, 2014	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Shares Available for Grant
Balance at the beginning of the year (in shares)	114,000				114,000	106,000	176,000
Additional shares authorized					250,000	50,000	50,000
RSUs granted (in shares)					(407,000)	(144,000)
RSUs cancelled and returned to Plan (in shares)					59,000	7,000	2,000
Options granted (in shares)		(334,027)			(160,000)	(384,000)	(154,000)
Options cancelled and returned to Plan (in shares)					375,000	479,000	70,000
Options expired (in shares)							(38,000)
Balance at the end of the year (in shares)					231,000	114,000	106,000	176,000
Number of Shares
Balance at the beginning of the period (in shares)	522,000				522,000	675,000	599,000
Options granted (in shares)					160,000	384,000	154,000
Options cancelled and returned to Plan (in shares)					(375,000)	(479,000)	(70,000)
Options cancelled and expired (in shares)		(456,995)				(58,000)
Options exercised (in shares)							8,000
Options expired (in shares)							(38,000)
Balance at the end of the period (in shares)					307,000	522,000	675,000	599,000
Weighted Average Exercise Prices
Weighted-average exercise price (in dollars per share)		$ 7.20			$ 4.81	$ 13.88	$ 35.10	$ 38.70
Options granted (in dollars per share)					0.76	6.96	20.20
Options cancelled and returned to Plan (in dollars per share)					$ 15.69	35.64	35.20
Options exercised (in dollars per share)							16.40
Options expired (in dollars per share)						$ 44.80	$ 32.00
Equity Incentive Plan2010 [Member]
Shares Available for Grant
Additional shares authorized	50,000
Amended2000 Plan [Member]
Shares Available for Grant
Balance at the beginning of the year (in shares)	0				0
Balance at the end of the year (in shares)					0	0
RSU's | Equity Incentive Plan2010 [Member]
Shares Available for Grant
RSUs granted (in shares)					(407,000)	(144,000)
RSUs cancelled and returned to Plan (in shares)					59,000	8,000	2,000
Options | Equity Incentive Plan2010 [Member]
Shares Available for Grant
Additional shares authorized				150,000				200,000
Employee stock purchase plan
Shares Available for Grant
Additional shares authorized			200,000
Balance at the end of the year (in shares)					150,000