7. Pension and Other Postretirement Benefit Plans

The components of net periodic pension cost for defined benefit pension and other postretirement benefit plans included in the Company’s results of operations are as follows:

	Three Months Ended September 30,
	2018			2017			2018			2017
(in millions)	Pension Plans						Postretirement Plans
Service cost - benefits earned during the period	$	—		$	—		$	—		$	—
Interest cost		5.0			5.4			0.1			0.1
Expected return on plan assets		(5.2	)		(5.3	)		—			—
Recognized net actuarial loss		2.4			3.4			—			—
Amortization of prior service cost		—			—			—			(0.3	)
Net periodic pension cost (benefit)	$	2.2		$	3.5		$	0.1		$	(0.2	)

	Nine Months Ended September 30,
	2018			2017			2018			2017
(in millions)	Pension Plans						Postretirement Plans
Service cost - benefits earned during the period	$	—		$	—		$	—		$	—
Interest cost		14.9			16.4			0.3			0.3
Expected return on plan assets		(15.5	)		(16.1	)		—			—
Recognized net actuarial loss		7.2			10.2			0.1			0.1
Amortization of prior service cost		—			—			(0.2	)		(1.0	)
Net periodic pension cost (benefit)	$	6.6		$	10.5		$	0.2		$	(0.6	)

Net periodic pension benefit for Chaucer’s pension plan of $0.7 million and $0.1 million for the three months ended September 30, 2018 and 2017, respectively, and $2.0 million and $0.2 million for the nine months ended September 30, 2018 and 2017, respectively, have been reported in discontinued operations and are not included in the amounts disclosed above.