Retirement Plans (Tables)

3 Months Ended

Mar. 31, 2016

Retirement Plans [Abstract]

Components of Net Periodic Benefits Cost

					Other Post-
(in thousands)	Pension Benefits				retirement Benefits
Three Months Ended March 31,	2016		2015		2016		2015
Service cost	$	3,265	$	3,363	$	29	$	50
Interest cost		4,988		4,619		206		369
Expected return on plan assets		(8,891)		(8,213)		—		—
Amortization of net loss		1,468		644		(31)		125
Net periodic benefit cost	$	830	$	413	$	204	$	544