Schedule II—Valuation and Qualifying Accounts (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Uncollectible accounts written off	$ 1,100,000	$ 200,000	$ 1,100,000
Allowance for doubtful accounts
Balance at Beginning of Period	2,589,000	1,379,000	1,605,000
Additions	(18,000)	1,266,000	847,000
Deductions	497,000	56,000	1,073,000
Balance at End of Period	2,074,000	2,589,000	1,379,000
Uncollectible accounts written off	$ 927,000	$ 200,000	$ 28,000