Pension plans and other postretirement benefits

6 Months Ended

Jun. 30, 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 defined benefit cost for defined benefit plans consisted of the following:

	Pension benefits						Other postretirement benefits
	Three months ended June 30
	2016			2015			2016			2015
	(in thousands)
Service cost	$	6,137			5,832			340			174
Interest cost on projected benefit obligation		20,822			17,732			1,281			652
Expected return on plan assets		(26,423	)		(23,476	)		—			—
Amortization of prior service credit		(789	)		(1,478	)		(330	)		(329	)
Amortization of net actuarial loss		6,773			11,237			30			28
Net periodic benefit cost	$	6,520			9,847			1,321			525
	Pension benefits						Other postretirement benefits
	Six months ended June 30
	2016			2015			2016			2015
	(in thousands)
Service cost	$	12,519			11,832			798			374
Interest cost on projected benefit obligation		41,705			35,507			2,486			1,302
Expected return on plan assets		(54,237	)		(47,051	)		—			—
Amortization of prior service credit		(1,614	)		(3,003	)		(680	)		(679	)
Amortization of net actuarial loss		15,073			22,412			30			53
Net periodic benefit cost	$	13,446			19,697			2,634			1,050

Expense incurred in connection with the Company’s defined contribution pension and retirement savings plans totaled $15,274,000 and $13,346,000 for the three months ended June 30, 2016 and 2015, respectively, and $32,964,000 and $30,096,000 for the six months ended June 30, 2016 and 2015, respectively.