| Components of Net Periodic Benefit (Income) Cost |
| | | | | | | | | | | | | | | | | | Pension Benefits | | Other Postretirement Benefits | | Three Months Ended
September 30, | | Three Months Ended
September 30, | | 2014 | | 2013 | | 2014 | | 2013 | Components of Net Periodic Benefit (Income) Cost | ($ in millions) | Service cost | $ | 1.3 |
| | $ | 1.6 |
| | $ | 0.2 |
| | $ | 0.3 |
| Interest cost | 21.5 |
| | 20.2 |
| | 0.5 |
| | 0.6 |
| Expected return on plans’ assets | (34.8 | ) | | (34.4 | ) | | — |
| | — |
| Amortization of prior service cost | — |
| | — |
| | — |
| | — |
| Recognized actuarial loss | 5.4 |
| | 7.4 |
| | 0.1 |
| | 0.7 |
| Net periodic benefit (income) cost | $ | (6.6 | ) | | $ | (5.2 | ) | | $ | 0.8 |
| | $ | 1.6 |
|
| | | | | | | | | | | | | | | | | | Pension Benefits | | Other Postretirement Benefits | | Nine Months Ended
September 30, | | Nine Months Ended
September 30, | | 2014 | | 2013 | | 2014 | | 2013 | Components of Net Periodic Benefit (Income) Cost | ($ in millions) | Service cost | $ | 4.0 |
| | $ | 4.7 |
| | $ | 0.8 |
| | $ | 1.0 |
| Interest cost | 64.9 |
| | 60.9 |
| | 2.0 |
| | 2.0 |
| Expected return on plans’ assets | (104.6 | ) | | (103.2 | ) | | — |
| | — |
| Amortization of prior service cost | 0.1 |
| | 0.1 |
| | (0.1 | ) | | (0.1 | ) | Recognized actuarial loss | 16.7 |
| | 22.2 |
| | 2.1 |
| | 2.8 |
| Net periodic benefit (income) cost | $ | (18.9 | ) | | $ | (15.3 | ) | | $ | 4.8 |
| | $ | 5.7 |
|
|