XML 104 R62.htm IDEA: XBRL DOCUMENT v3.19.3.a.u2
Benefit Plans Net Periodic Benefit Cost (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Pension Plan [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Service cost $ 5,947 $ 5,790 $ 4,699
Interest cost 8,506 6,879 6,993
Expected return on assets (10,118) (9,255) (7,888)
Amortization of prior service cost 48 51 94
Recognized actuarial loss 3,984 3,986 3,844
Net periodic pension cost 8,367 7,451 7,742
Other Postretirement Benefits Plan [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Service cost 581 616 529
Interest cost 775 627 634
Expected return on assets (475) (450) (376)
Amortization of prior service cost 197 197 198
Recognized actuarial loss 240 321 273
Net periodic pension cost $ 1,318 $ 1,311 $ 1,258