Schedule II - Valuation and Qualifying Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Movement in Valuation Allowances and Reserves [Roll Forward]
Allowance for doubtful accounts, balance at beginning of year	$ 261	$ 220	$ 102
Additions charged to costs and expenses	602	699	754
Deductions charged to costs and expenses	(656)	(658)	(636)
Allowance for doubtful accounts, balance at end of year	$ 207	$ 261	$ 220