XML 18 R6.htm IDEA: XBRL DOCUMENT v3.19.1
CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Parenthetical) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Statement of Comprehensive Income [Abstract]      
Amount of tax expense (benefit) for (increase) decrease in value of benefit obligation $ 173 $ 232 $ 7