Pension plans and other postretirement benefits

3 Months Ended

Mar. 31, 2016

Compensation and Retirement Disclosure [Abstract]

Pension plans and other postretirement benefits

7. Pension plans and other postretirement benefits

The Company provides defined benefit pension and other postretirement benefits (including health care and life insurance benefits) to qualified retired employees. Net periodic pension expense for defined benefit plans consisted of the following:

	Pension benefits						Other postretirement benefits
	Three months ended March 31
	2016			2015			2016			2015
	(in thousands)
Service cost	$	6,382			6,000			458			200
Interest cost on projected benefit obligation		20,883			17,775			1,205			650
Expected return on plan assets		(27,814	)		(23,575	)		—			—
Amortization of prior service credit		(825	)		(1,525	)		(350	)		(350	)
Amortization of net actuarial loss		8,300			11,175			—			25
Net periodic benefit cost	$	6,926			9,850			1,313			525

Expense incurred in connection with the Company’s defined contribution pension and retirement savings plans totaled $17,690,000 and $16,750,000 for the three months ended March 31, 2016 and 2015, respectively.