Income Taxes (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2013 Federal [Member]	Dec. 31, 2002 Federal [Member]	Dec. 31, 2013 State [Member]
Operating Loss Carryforwards [Line Items]
Period of time for IRS enforced limitation of NOL carryforward on company after an ownership change	3 years
Operating loss carryforwards, restricted				$ 4,000,000	$ 10,100,000
Operating loss carryforwards, unrestricted	164,900,000			191,900,000		112,400,000
Operating loss carryforwards annually				363,000
Tax credit carryforward related to research and development	9,900,000
Tax credit carryforwards related to alternative minimum tax	13,500,000
Expiration date	2022 through 2033
Deferred tax valuation allowance has been recorded against these assets (in hundredths)	100.00%
Deferred tax assets [Abstract]
Net operating loss carryforwards	69,989,000	60,184,000
Tax credit carryforwards	18,816,000	15,514,000
Equipment, furnishings and other	11,313,000	9,822,000
Total deferred tax assets	100,118,000	85,520,000
Deferred tax liabilities	(92,000)	(100,000)
Net deferred tax assets	100,026,000	85,420,000
Valuation allowance	(100,026,000)	(85,420,000)
Deferred Tax Assets, Net of Valuation Allowance	0	0
Net change in valuation allowance	14,600,000	14,100,000
Federal statutory rate to net loss before income taxes [Abstract]
Federal benefit at statutory rate	(16,145,000)	(6,107,000)	(4,996,000)
State income taxes, net of Federal taxes	(1,517,000)	(745,000)	(857,000)
State credits	(787,000)	(1,555,000)
Warranty liabilities	6,871,000	941,000
Other permanent differences	14,000	(23,000)	6,000
Provision related to change in valuation allowance	14,606,000	14,069,000	16,235,000
Other, net	(3,040,000)	(6,578,000)	(10,290,000)
Provision for income taxes	1,600	1,600	97,996
Change in unrecognized tax benefits	0
Unrecognized tax benefits accrued interest or penalties	$ 0	$ 0	$ 0