Income Taxes (Details 3) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 1987
Income Taxes
Period for which prior cumulative losses considered in assessing the realization of deferred tax assets	2 years
Cumulative percentage changes in shareholders' ownership to constitute ownership change (as a percent)	5.00%
Minimum basis percentage points, increase (as a percent)	50.00%
Percentage of ownership to be treated as a certain group under Section 382	5.00%
Testing period for measuring the percentage points increase	3 years
Tax bad debt reserve			$ 3,000,000
Deferred tax liability not recorded on tax bad debt reserve balance	1,000,000	1,000,000
Reconciliation of the beginning and ending amount of unrecognized tax benefits
Balance at beginning of year	431,000	323,000
Additions based on tax positions related to the current year	86,000	108,000
Reductions for tax positions of prior years	(29,000)
Balance at end of year	488,000	431,000
Unrecognized tax benefits if recognized would favorably affect income tax provision in future	488,000
Interest accrued during the period related to unrecognized tax benefits	3,000	4,000
Federal
Income taxes
Net operating loss carryforwards	13,300,000
California
Income taxes
Net operating loss carryforwards	$ 31,100,000