Allowance for Doubtful Accounts (Tables)

12 Months Ended

Dec. 31, 2017

Receivables [Abstract]

Allowance for Doubtful Debts

In order to provide for these collection problems and the general risk associated with the granting of credit terms, the Company recorded the following bad debt provisions (in an Allowance for Doubtful Accounts):

	Year Ended December 31,
	2017		2016		2015
	(in thousands)
Bad debt provision	$	6,250	$	4,629	$	4,335

Impaired Notes Receivable

Summary schedules of impaired notes receivable, and the related reserve, for the years ended December 31, 2017, 2016 and 2015 are as follows:

	Impaired Notes Receivable
Year Ended December 31,	Balance Beginning of Year		Additions		Deductions		Balance End of Year		Average Outstanding Balance
	(in thousands)
2017	$	5,685	$	1,169	$	—	$	6,854	$	6,270
2016	$	6,471	$	—	$	786	$	5,685	$	6,078
2015	$	10,208	$	395	$	4,132	$	6,471	$	8,340

	Reserve for Impaired Notes Receivable
Year Ended December 31,	Balance Beginning of Year		Additions		Deductions		Balance End of Year
	(in thousands)
2017	$	2,419	$	465	$	—	$	2,884
2016	$	2,139	$	280	$	—	$	2,419
2015	$	3,031	$	99	$	991	$	2,139