Employee Benefit Plans (Tables)

9 Months Ended

Sep. 30, 2018

Compensation And Retirement Disclosure [Abstract]

Schedule of components of period benefit costs

The components of periodic benefit costs for the three and nine months ended September 30, 2018 and September 30, 2017 are as follows:

	Three Months Ended September 30, 2018									Nine Months Ended September 30, 2018
							Postretirement									Postretirement
	U.S.			Non-U.S.			Health and			U.S.			Non-U.S.			Health and
	Pension			Pension			Other			Pension			Pension			Other
($ in millions)	Plans			Plans			Plans			Plans			Plans			Plans
Service cost - benefits earned during the period	$	—		$	0.5		$	0.1		$	—		$	1.5		$	0.3
Interest cost of projected benefit obligations		1.3			0.5			0.2			3.9			1.5			0.6
Expected return on plan assets		(1.5	)		(0.4	)		—			(4.5	)		(1.2	)		—
Amortization of prior service cost		—			—			(0.7	)		—			—			(2.1	)
Amortization of actuarial net loss		0.8			0.4			0.2			2.4			1.2			0.6
Pension settlement charge		4.5			—			—			4.5			—			—
Net periodic benefit costs	$	5.1		$	1.0		$	(0.2	)	$	6.3		$	3.0		$	(0.6	)

	Three Months Ended September 30, 2017									Nine Months Ended September 30, 2017
							Postretirement									Postretirement
	U.S.			Non-U.S.			Health and			U.S.			Non-U.S.			Health and
	Pension			Pension			Other			Pension			Pension			Other
($ in millions)	Plans			Plans			Plans			Plans			Plans			Plans
Service cost - benefits earned during the period	$	—		$	0.4		$	0.1		$	—		$	1.3		$	0.2
Interest cost of projected benefit obligations		1.3			0.6			0.2			4.0			1.6			0.7
Expected return on plan assets		(1.2	)		(0.4	)		—			(3.7	)		(1.1	)		—
Amortization of prior service cost		—			—			(0.3	)		—			—			(1.0	)
Amortization of actuarial net loss		0.8			0.4			0.1			2.4			1.2			0.3
Net periodic benefit costs		0.9			1.0			0.1			2.7			3.0			0.2