XML 17 R6.htm IDEA: XBRL DOCUMENT v3.7.0.1
Statements of Consolidated Comprehensive Income (Unaudited) (Parenthetical) - USD ($)
$ in Thousands
3 Months Ended 6 Months Ended
Jun. 30, 2017
Jun. 30, 2016
Jun. 30, 2017
Jun. 30, 2016
Comprehensive Income Net Of Tax [Abstract]        
Net of tax provision on recognized net actuarial gain $ 49 $ 46 $ 93 $ 92