Receivables and Allowance for Doubtful Accounts Receivables and Allowance for Doubtful Accounts (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Receivables [Line Items]
Accounts Receivable, Gross	$ 68,229		$ 74,528
Receivables, net of allowance for doubtful accounts of $4,468 and $4,883 in 2019 and 2018, respectively	63,761		69,645
Allowance for Doubtful Accounts Receivable [Roll Forward]
Bad debt expense	2,942	$ 3,437
Accounts written off	(3,544)
Recoveries	187
Allowance for doubtful accounts	4,468		4,883
Installment sales receivable [Member]
Receivables [Line Items]
Accounts Receivable, Gross	51,534		54,746
Allowance for Doubtful Accounts Receivable [Roll Forward]
Allowance for doubtful accounts	3,100		3,600
Trade and notes receivables [Member]
Receivables [Line Items]
Accounts Receivable, Gross	16,695		19,782
Allowance for Doubtful Accounts Receivable [Roll Forward]
Allowance for doubtful accounts	$ 1,400		$ 1,300