Pension and Other Postretirement Benefits (Tables)

9 Months Ended

Sep. 30, 2015

Pension and Other Postretirement Benefit Expense [Abstract]

Summary of Net Periodic Pension and Other Postemployment Benefit Costs

Net periodic pension cost recognized during the periods included the following components (in thousands):

	Three months ended September 30,						Nine months ended September 30,
	2015			2014			2015			2014
Service cost	$	4,281		$	3,701		$	12,705		$	10,981
Interest cost	8,035			8,272			23,843			24,547
Expected return on plan assets	(10,645		)	(10,479		)	(31,589		)	(31,094		)
Amortization of net loss	6,450			4,947			19,139			14,684
Amortization of prior service credit	(1,140		)	(1,134		)	(3,381		)	(3,366		)
Total net pension cost	$	6,981		$	5,307		$	20,717		$	15,752

Other postretirement benefit cost recognized during the periods included the following components (in thousands):

	Three months ended September 30,					Nine months ended September 30,
	2015		2014			2015			2014
Service cost	$	327	$	272		$	971		$	809
Interest cost	711		774			2,109			2,297
Amortization of net loss	—		(40		)	(2		)	(119		)
Amortization of prior service credit	—		(8		)	—			(24		)
Total other postretirement benefit cost	$	1,038	$	998		$	3,078		$	2,963