Summary of Significant Accounting Policies Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2017

Accounting Policies [Abstract]

Allowance for Doubtful Accounts Receivable

Additions, deductions and balances for allowance for doubtful accounts for 2017, 2016 and 2015 are as follows (in thousands):

	2017		2016		2015
Balance at beginning of year	$	2,156	$	2,046	$	2,253
Additions:
Charged to costs and expense	3,141		2,427		2,057
Recovery of previous write-offs	1,122		1,395		1,613
Uncollectible receivables written off	4,119		3,712		3,877
Balance at end of year	$	2,300	$	2,156	$	2,046