5. Pension and Other Retiree Benefits

The components of net periodic benefit (income) cost for pension and post-retirement plans for the three and nine months ended September 30, 2017 and 2016 were as follows:



	Three Months Ended September 30,
	Pension												Post-retirement
	U.S.						International
(in millions of dollars)	2017			2016			2017			2016			2017			2016
Service cost	$	0.3		$	0.4		$	0.4		$	0.2		$	—		$	—
Interest cost	1.8			1.8			3.6			2.5			—			—
Expected return on plan assets	(3.1		)	(2.9		)	(5.6		)	(4.2		)	—			—
Amortization of net loss (gain)	0.5			0.4			0.7			0.5			(0.1		)	(0.1		)
Amortization of prior service cost	0.1			0.1			—			—			—			—
Curtailment gain	—			—			—			—			—			(0.6		)
Net periodic benefit income	$	(0.4	)	$	(0.2	)	$	(0.9	)	$	(1.0	)	$	(0.1	)	$	(0.7	)

	Nine Months Ended September 30,
	Pension												Post-retirement
	U.S.						International
(in millions of dollars)	2017			2016			2017			2016			2017			2016
Service cost	$	1.0		$	1.0		$	1.2		$	0.6		$	—		$	—
Interest cost	5.3			5.4			10.0			7.9			0.1			0.2
Expected return on plan assets	(9.2		)	(8.9		)	(16.1		)	(13.4		)	—			—
Amortization of net loss (gain)	1.5			1.4			2.2			1.7			(0.3		)	(0.3		)
Amortization of prior service cost	0.3			0.3			—			—			—			—
Curtailment gain	—			—			—			—			—			(0.6		)
Net periodic benefit income	$	(1.1	)	$	(0.8	)	$	(2.7	)	$	(3.2	)	$	(0.2	)	$	(0.7	)

We expect to contribute approximately $20.9 million to our defined benefit plans in 2017, which includes approximately $8.7 million for Esselte defined benefit plans. For the nine months ended September 30, 2017, we contributed $17.1 million to these plans.

The Esselte Acquisition added $171.5 million in pension obligations, as of January 31, 2017. The obligations under the acquired German pension plan represent $133.7 million of this amount. German pension law does not require pre-funding of pension obligations and thus the plan is not funded.