Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2017

Commitments and Contingencies Disclosure [Abstract]

Schedule of Future Minimum Rental Payments for Operating Leases

At December 31, 2017, future minimum rental payments under non-cancelable operating leases were:

Year	($ in millions)
2018	$	13.2
2019	11.4
2020	8.5
2021	6.7
2022	6.2
Thereafter	33.1
Total	$	79.1