Schedule II Valuation Accounts (Details) - Allowance For Doubtful Accounts [Member] - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period		$ 548	$ 680	$ 503
Net Additions (Reductions) to Expense		3,151	448	248
Deductions	[1]	(2,359)	(580)	(71)
Balance at End of Period		$ 1,340	$ 548	$ 680

[1] Primarily consists of write-offs, net of recoveries and other adjustments