12. RETIREMENT PLANS

The Company’s most significant retirement plan is the U.S. plan for which the benefits are based on an average of the employee’s earnings in the years preceding retirement and on credited service. In a prior year, the Company closed participation in the Autoliv ASP, Inc. Pension Plan to exclude those employees hired after December 31, 2003. Within the U.S. there is also a non-qualified restoration plan that provides benefits to employees whose benefits in the primary U.S. plan are restricted by limitations on the compensation that can be considered in calculating their benefits. In December 2017 the Company decided to amend the U.S. defined pension plan, communicating a benefits freeze that will begin on December 31, 2021.

For the Company’s non-U.S. defined benefit plans the most significant individual plan resides in the U.K. The Company has closed participation in the U.K. defined benefit plan to exclude all employees hired after April 30, 2003 with few members accruing benefits.

The Net Periodic Benefit Costs related to Other Post-retirement Benefits were not significant to the condensed consolidated financial statements of the Company for the three month periods ended March 31, 2018 and March 31, 2017 and are not included in the table below.

The components of total Net Periodic Benefit Cost associated with the Company’s defined benefit retirement plans are as follows:

	Three months ended
	March 31, 2018			March 31, 2017
Service cost	$	6.4		$	6.0
Interest cost		5.1			5.3
Expected return on plan assets		(6.2	)		(5.3	)
Amortization prior service cost		0.1			0.1
Amortization of actuarial loss		0.9			2.0
Net Periodic Benefit Cost	$	6.3		$	8.1

The Service cost and Amortization of prior service cost components are reported among other employee compensation costs in the Consolidated Statements of Income. The remaining components Interest cost, Expected return on plan assets and Amortization of actuarial loss are reported as Other non-operating items, net in the Consolidated Statements of Income.