XML 66 R31.htm IDEA: XBRL DOCUMENT v3.20.1
Employee and Retiree Benefit Plans (Tables)
 3 Months Ended
Mar. 31, 2020
Retirement Benefits [Abstract]  
Components of Net Periodic Benefit Expense
The table that follows provides the components of net periodic benefit expense for the three-month periods ended March 31, 2020 and 2019.
 
Three Months Ended March 31,
 
Pension Benefits
 
Other Postretirement Benefits
(Thousands of dollars)
2020
 
2019
 
2020
 
2019
Service cost
$
2,166

 
2,062

 
447

 
420

Interest cost
5,791

 
7,151

 
794

 
945

Expected return on plan assets
(6,344
)
 
(6,460
)
 
—

 
—

Amortization of prior service cost (credit)
183

 
247

 
—

 
(98
)
Recognized actuarial loss
4,269

 
3,514

 
—

 
—

Net periodic benefit expense
$
6,065

 
6,514

 
1,241

 
1,267