Retirement Plans (Tables)

9 Months Ended

Sep. 30, 2018

Retirement Plans [Abstract]

Components of Net Periodic Benefits Cost

					Other Post-
(in thousands)	Pension Benefits				Retirement Benefits
Three Months Ended September 30, 2018	2018		2017		2018		2017
Service cost	$	3,163	$	3,769	$	28	$	17
Interest cost		4,279		4,056		161		155
Expected return on plan assets		(10,375)		(9,652)		—		—
Amortization of net loss and prior service costs		1,366		1,167		(95)		(128)
Net periodic benefit cost (reduction of cost)	$	(1,567)	$	(660)	$	94	$	44
					Other Post-
(in thousands)	Pension Benefits				Retirement Benefits
Nine Months Ended September 30, 2018	2018		2017		2018		2017
Service cost	$	9,251		11,612	$	91		112
Interest cost		12,481		12,470		459		514
Expected return on plan assets		(30,244)		(27,978)		—		—
Amortization of net loss and prior service costs		4,057		4,368		(338)		(224)
Net periodic benefit cost (reduction of cost)	$	(4,455)	$	472	$	212	$	402