XML 114 R99.htm IDEA: XBRL DOCUMENT v3.8.0.1
Valuation and Qualifying Accounts (Detail) - Allowance for Doubtful Accounts - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Valuation And Qualifying Accounts Disclosure [Line Items]      
Beginning Balance $ 3,191 $ 3,545 $ 3,546
Deductions [1] (868) (354) (1)
Ending Balance $ 2,323 $ 3,191 $ 3,545
[1] Consists of uncollectible accounts written off