Schedule II - Valuation and Qualifying Accounts: (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Balance at beginning of year	$ 67,000	$ 59,000
Charged to expenses	30,000	21,000
Uncollectible accounts written off	(2,000)	(10,000)
Balance at end of year	$ 99,000	$ 67,000