v3.4.0.3
Employee Benefits (Tables)
 3 Months Ended
Mar. 31, 2016
Compensation and Retirement Disclosure [Abstract]  
Schedule of the components of net periodic benefit cost
The following tables show the components of net periodic pension and OPEB costs for our benefit plans. Our pension and OPEB costs for the three months ended March 31, 2016, include costs attributable to the Integrys pension and OPEB plans. The terms and conditions of the legacy company plans have not changed since the acquisition.
 
 
Pension Costs
 
 
Three Months Ended March 31
(in millions)
 
2016
 
2015
Service cost
 
$
11.3

 
$
3.9

Interest cost
 
33.2

 
15.2

Expected return on plan assets
 
(49.0
)
 
(25.8
)
Amortization of prior service cost
 
0.9

 
0.5

Amortization of net actuarial loss
 
20.5

 
11.6

Net periodic benefit cost
 
$
16.9

 
$
5.4


 
 
OPEB Costs
 
 
Three Months Ended March 31
(in millions)
 
2016
 
2015
Service cost
 
$
6.7

 
$
2.6

Interest cost
 
9.2

 
4.2

Expected return on plan assets
 
(13.1
)
 
(5.9
)
Amortization of prior service credit
 
(2.3
)
 
(0.3
)
Amortization of net actuarial loss
 
2.3

 
0.5

Net periodic benefit cost
 
$
2.8

 
$
1.1