Schedule II - Valuation and Qualifying Accounts (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance, beginning of period	$ 153,000	$ 662,000	$ 525,000
Charged to Revenues and Expenses	85,000	1,576,000	2,359,000
Deductions	(151,000)	(2,085,000)	(2,222,000)
Balance, end of period	87,000	153,000	662,000
Reduction to revenues	$ 0	$ 1,600,000	$ 2,200,000