EMPLOYEE BENEFIT AND RETIREMENT PLANS

During the first quarter of 2018, our Management Committee approved the freezing of benefits under our pension plans in Canada. The effective date of this freeze is November 30, 2019. Although those plans will be frozen, employees who are participants in the plans will retain benefits accumulated up to the date of the freeze, based on credited service and eligible earnings, in accordance with the terms of the plans.

As a result of this change, we remeasured pension assets and benefit obligations as of the date of the approval (December 1, 2017) and we reduced the Canadian plan benefit obligations by $17.5 million. This remeasurement resulted in non-cash, pre-tax net actuarial gains of $17.5 million for the three months ended February 28, 2018. This net actuarial gain consists principally of a curtailment gain of $18.0 million and is included in our consolidated statement of comprehensive income for the three months ended February 28, 2018, as a component of Other comprehensive income (loss) on the line entitled Unrealized components of pension plans. Deferred taxes associated with these actuarial gains, together with other unrealized components of pension plans recognized during the three months ended February 28, 2018, is also included in that statement as a component of Other comprehensive income (loss).

The following table presents the components of our pension expense of the defined benefit plans for the three months ended February 28, 2019 and 2018 (in millions):



	United States						International
	2019			2018			2019			2018
Defined benefit plans
Service cost	$	0.5		$	4.4		$	0.9		$	1.1
Interest costs	8.6			7.9			2.4			2.4
Expected return on plan assets	(10.6		)	(10.8		)	(4.1		)	(4.2		)
Amortization of prior service costs	0.1			—			—			0.5
Amortization of net actuarial losses	0.6			2.5			0.3			0.7
Total pension expense	$	(0.8	)	$	4.0		$	(0.5	)	$	0.5

During the three months ended February 28, 2019 and 2018, we contributed $1.9 million and $5.9 million, respectively, to our pension plans. Total contributions to our pension plans in fiscal year 2018 were $13.5 million.

The following table presents the components of our other postretirement benefits expense (in millions):



	Three months ended February 28,
	2019			2018
Other postretirement benefits
Service cost	$	0.5		$	0.6
Interest costs	0.7			0.6
Amortization of prior service credits	(2.2		)	(2.2		)
Amortization of net actuarial gains	(0.2		)	—
Total other postretirement benefits expense	$	(1.2	)	$	(1.0	)

In conjunction with our adoption of the Pension ASU, all of the amounts in the tables above for pension expense and other postretirement benefits expense, other than service cost, were included in the income statement caption "Other income, net" within our consolidated income statements. The aggregate amount of non-service costs were income of $4.4 million and $2.6 million for the three months ended February 28, 2019 and 2018, respectively.