Schedule II - Valuation and Qualifying Accounts (Details) - Allowance for Doubtful Accounts - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Balance at Beginning of Period	$ 2,074	$ 2,589	$ 1,379
Additions	161	(18)	1,266
Deductions	1,014	497	56
Balance at End of Period	$ 1,221	$ 2,074	$ 2,589