Property and Equipment (Details) (USD $)	3 Months Ended
Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Property and equipment
Property and equipment, gross	$ 6,871,000		$ 6,499,000
Less accumulated depreciation and amortization	(5,184,000)		(5,078,000)
Property and equipment, net	1,687,000		1,421,000
Depreciation expense	106,000	167,000
Computer equipment
Property and equipment
Property and equipment, gross	623,000		615,000
Software
Property and equipment
Property and equipment, gross	209,000		209,000
Lab equipment and furniture
Property and equipment
Property and equipment, gross	4,236,000		3,896,000
Leasehold improvements
Property and equipment
Property and equipment, gross	$ 1,803,000		$ 1,779,000

The cumulative amount of depreciation, depletion and amortization (related to property, plant and equipment, but not including land) that has been recognized in the income statement.

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The amount of expense recognized in the current period that reflects the allocation of the cost of tangible assets over the assets' useful lives. Includes production and non-production related depreciation.

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- Definition

Gross amount of long-lived physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

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- Definition

Amount, net of accumulated depreciation, depletion and amortization, of long-lived physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

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