Commitments and Contingencies Narrative (Details) (USD $)	3 Months Ended		12 Months Ended
	Mar. 31, 2013 lease	Mar. 31, 2012	Dec. 31, 2011 lease	Dec. 31, 2012	Nov. 30, 2010 Comerica Bank [Member]	Mar. 31, 2013 Lease 1 [Member]	Dec. 31, 2011 Lease 1 [Member]	Mar. 31, 2013 Lease 2 [Member]	Dec. 31, 2011 Lease 2 [Member]	Mar. 31, 2013 Lease 3 [Member]
Long-term Purchase Commitment [Line Items]
Operating lease payments	$ 191,000	$ 128,000
Number of non-cancelable lease agreements	3		2
Value of non-cancelable capital lease agreements						90,000	512,000	30,000	40,000	48,000
Interest rates on non-cancelable capital lease agreements						9.00%	6.00%	3.00%	0.00%	0.00%
Depreciation expense on the equipment under the capital leases	40,000	29,000
Current portion of capital lease	243,000			240,000
Capital lease, net of current portion	169,000			231,000
Letters of credit outstanding, amount					$ 115,000