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Pension Plans And Other Postretirement Benefit Plans (Tables)
 6 Months Ended
Jun. 30, 2018
Components of Net Periodic Benefit Cost
 
Pension Benefits
 
Other Postretirement Benefits
 
2018
 
2017
 
2018
 
2017
Three months ended June 30:
 
 
 
 
 
 
 
Service cost (a)
$
5,450

 
$
5,092

 
$
804

 
$
799

Interest cost
6,466

 
6,976

 
1,197

 
1,374

Expected return on plan assets
(8,250
)
 
(7,900
)
 
(500
)
 
(475
)
Amortization of prior service cost
75

 
—

 
209

 
(312
)
Net loss recognition
1,842

 
2,317

 
562

 
1,320

Net periodic benefit cost
$
5,583

 
$
6,485

 
$
2,272

 
$
2,706

Six months ended June 30:
 
 
 
 
 
 
 
Service cost (a)
$
10,900

 
$
10,134

 
$
1,608

 
$
1,623

Interest cost
12,932

 
13,927

 
2,394

 
2,773

Expected return on plan assets
(16,500
)
 
(15,800
)
 
(1,000
)
 
(950
)
Amortization of prior service cost
150

 
—

 
(606
)
 
(624
)
Net loss recognition
3,930

 
4,863

 
2,217

 
2,593

Net periodic benefit cost
$
11,412

 
$
13,124

 
$
4,613

 
$
5,415


(a)
Total service costs in the table above are recorded to the same accounts as labor expense. Labor and benefits expense is recorded to various projects based on whether the work is a capital project or an operating expense. Approximately 40 percent of all labor and benefits is capitalized to utility property and 60 percent is expensed to utility other operating expenses.