Pension Plans (Tables)

3 Months Ended

Mar. 31, 2018

Retirement Benefits [Abstract]

Components of net periodic pension cost

The components of net periodic pension cost for these defined benefit pension plans are as follows:

	For the Three Months Ended March 31,
	2018			2017
	(In thousands)
Service cost	$	8,416		$	8,340
Interest cost	1,243			1,007
Expected return on plan assets	(1,442		)	(1,128		)
Amortization of prior service cost	—			31
Recognized actuarial (gain) loss	(35		)	22
Net periodic pension cost	$	8,182		$	8,272

Summary of defined contribution expense

The following table summarizes our defined contribution expense:

	For the Three Months Ended March 31,
	2018		2017
	(In thousands)
Defined contribution expense	$	3,996	$	3,198