Retirement Plans (Tables)

9 Months Ended

Sep. 30, 2016

Retirement Plans [Abstract]

Components of Net Periodic Benefits Cost

					Other Post-
(in thousands)	Pension Benefits				retirement Benefits
Three Months Ended September 30, 2016	2016		2015		2016		2015
Service cost	$	3,611	$	3,383	$	45	$	23
Interest cost		4,022		4,672		204		174
Expected return on plan assets		(8,554)		(8,207)		—		—
Amortization of net loss		1,426		842		53		(40)
Net periodic benefit cost	$	505	$	690	$	302	$	157
Nine Months Ended September 30, 2016
Service cost	$	10,487	$	10,128	$	119	$	95
Interest cost		13,033		13,963		613		717
Expected return on plan assets		(25,999)		(24,626)		—		—
Amortization of net loss		4,320		2,328		75		45
Net periodic benefit cost	$	1,841	$	1,793	$	807	$	857