Retirement Plans (Tables)

9 Months Ended

Sep. 30, 2018

Defined Benefit Pension Plans

Net Periodic Pension and Postretirement benefit Cost (Income)

For the three and nine months ended September 30, 2018 and October 1, 2017, Teradyne’s net periodic pension cost was comprised of the following:

	For the Three Months Ended
	September 30, 2018						October 1, 2017
	United States			Foreign			United States			Foreign
	(in thousands)
Service cost	$	538		$	203		$	560		$	215
Interest cost		1,750			177			3,288			186
Expected return on plan assets		(1,551	)		(5	)		(3,002	)		(6	)
Amortization of prior service cost		14			—			18			—
Settlement loss		267			—			—			—
Total net periodic pension cost	$	1,018		$	375		$	864		$	395

	For the Nine Months Ended
	September 30, 2018						October 1, 2017
	United States			Foreign			United States			Foreign
	(in thousands)
Service cost	$	1,657		$	609		$	1,679		$	606
Interest cost		7,188			532			9,863			527
Expected return on plan assets		(7,484	)		(15	)		(9,006	)		(19	)
Amortization of prior service cost		43			—			53			—
Net actuarial gain		(189	)		—			(2,732	)		243
Settlement loss		345			—			—			—
Total net periodic pension cost (benefit)	$	1,560		$	1,126		$	(143	)	$	1,357

Postretirement Benefit Plans

Net Periodic Pension and Postretirement benefit Cost (Income)

For the three and nine months ended September 30, 2018 and October 1, 2017, Teradyne’s net periodic postretirement benefit cost (income) was comprised of the following:

	For the Three Months Ended						For the Nine Months Ended
	September 30, 2018			October 1, 2017			September 30, 2018			October 1, 2017
	(in thousands)
Service cost	$	10		$	8		$	29		$	25
Interest cost		49			50			147			151
Amortization of prior service credit		(93	)		(124	)		(280	)		(372	)
Net actuarial loss (gain)		—			—			40			(15	)
Special termination benefits		601			—			3,419			—
Total net periodic postretirement benefit cost (income)	$	567		$	(66	)	$	3,355		$	(211	)