Summary of Significant Accounting Policies (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Allowance For Doubtful Accounts Receivable Rollforward [Line Items]
Balance at Beginning of Period	$ 518	$ 614	$ 378
Charged to Costs and Expenses	333	195	294
Allowance From Acquisitions	181	0	99
Write Off of Uncollectible Accounts, Net of Recoveries	(305)	(291)	(157)
Balance at End of Period	$ 727	$ 518	$ 614