Benefit Plans

Components of net periodic benefit cost for our pension plans for the three and nine months ended September 30, 2018 and 2017 were as follows:



	Three months ended						Nine months ended
In millions	September 30, 2018			September 30, 2017			September 30, 2018			September 30, 2017
Service cost	$	1.0		$	2.9		$	3.1		$	8.8
Interest cost	3.0			4.1			9.0			12.3
Expected return on plan assets	(2.2		)	(2.9		)	(6.7		)	(8.7		)
Actuarial loss	2.2			—			2.2			—
Net periodic benefit cost	$	4.0		$	4.1		$	7.6		$	12.4

In November 2017, our Board of Directors approved amendments to terminate the Pentair Salaried Plan (the “Salaried Plan”), a U.S. qualified pension plan. The Salaried Plan discontinued accruing benefits on December 31, 2017 and the termination was effective December 31, 2017. It is expected to take 18 to 24 months from the date of the approved amendment to complete the termination of the Salaried Plan.

Salaried Plan participants whose benefits were not in pay status by July 1, 2018 were given the opportunity to elect a lump-sum (or monthly annuity) payment during a special election window. During the third quarter of 2018, lump-sum payments of $171.9 million resulted in interim mark-to-market accounting for the Salaried Plan. The mark-to-market adjustment is reflected within Actuarial loss in the table above.

As described in Note 1, during the first quarter of 2018, the Company adopted ASU 2017-07. As a result, service costs are classified as employee compensation costs within Cost of goods sold and Selling, general and administrative expense within the Condensed Consolidated Statements of Operations and Comprehensive Income. All other components of net periodic benefit cost are classified within Other expense (income) for the periods presented.

Components of net periodic benefit cost for our other post-retirement plans for the three and nine months ended September 30, 2018 and 2017 were not material.