Benefit Plans

The components of net periodic benefit cost for the three months ended June 30 were as follows ($ in millions):



	Pension benefits						Other retirement benefits						Total
	2015			2014			2015			2014			2015			2014
Service cost	$	2.7		$	2.5		$	0.2		$	0.1		$	2.9		$	2.6
Interest cost	3.9			4.3			0.1			0.1			4.0			4.4
Expected return on assets	(5.7		)	(4.8		)	—			—			(5.7		)	(4.8		)
Amortization of prior service credit	(0.3		)	(0.3		)	—			—			(0.3		)	(0.3		)
Recognized actuarial losses (gains)	1.6			1.1			(0.4		)	(0.3		)	1.2			0.8
Net periodic benefit cost	$	2.2		$	2.8		$	(0.1	)	$	(0.1	)	$	2.1		$	2.7

The components of net periodic benefit cost for the six months ended June 30 were as follows ($ in millions):



	Pension benefits						Other retirement benefits						Total
	2015			2014			2015			2014			2015			2014
Service cost	$	5.4		$	5.1		$	0.3		$	0.2		$	5.7		$	5.3
Interest cost	7.8			8.5			0.2			0.2			8.0			8.7
Expected return on assets	(11.4		)	(9.7		)	—			—			(11.4		)	(9.7		)
Amortization of prior service credit	(0.6		)	(0.6		)	—			—			(0.6		)	(0.6		)
Recognized actuarial losses (gains)	3.2			2.3			(0.7		)	(0.7		)	2.5			1.6
Net periodic benefit cost	$	4.4		$	5.6		$	(0.2	)	$	(0.3	)	$	4.2		$	5.3