Summary of Significant Accounting Policies - Schedule of Allowances Against Accounts and Notes Receivable (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Receivables [Abstract]
Balance at beginning of period	$ 5,535	$ 4,483	$ 4,495
Additions/charges to cost and expense for doubtful accounts	1,159	1,325	353
Additions and charges to cost and expense for allowances for doubtful accounts	1,109	1,195	433
Deductions/ write-offs	(491)	(273)	(365)
Balance at end of period	$ 6,203	$ 5,535	$ 4,483