XML 100 R87.htm IDEA: XBRL DOCUMENT v3.19.1
Benefit Plans (Fair values of our pension plan assets by asset category) (Details) - USD ($)
$ in Thousands
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]      
Fair values of the Corporation's pension plan assets $ 7,765 $ 9,469 $ 9,325
Level 2 [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Fair values of the Corporation's pension plan assets 7,765 9,469  
Short-term investments [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Fair values of the Corporation's pension plan assets 98 300  
Short-term investments [Member] | Level 2 [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Fair values of the Corporation's pension plan assets 98 300  
Fixed income [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Fair values of the Corporation's pension plan assets 2,924 3,815  
Fixed income [Member] | Level 2 [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Fair values of the Corporation's pension plan assets 2,924 3,815  
Equity investments [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Fair values of the Corporation's pension plan assets 4,743 5,354  
Equity investments [Member] | Level 2 [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Fair values of the Corporation's pension plan assets $ 4,743 $ 5,354