Schedule II - Valuation and Qualifying Accounts (Details) (Allowance for Doubtful Accounts [Member], USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Allowance for Doubtful Accounts [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of year	$ 100,000	$ 100,000	$ 100,000
Charged to (credited to) costs and expenses	0	0	59,297
Deductions	0	0	59,297
Balance at end of year	$ 100,000	$ 100,000	$ 100,000