Retirement Plans (Tables)

3 Months Ended

Mar. 31, 2019

Compensation And Retirement Disclosure [Abstract]

Components of Net Periodic Benefits Cost

							Other Post-
(in thousands)	Pension Benefits						Retirement Benefits
For the Three Months Ended March 31,	2019			2018			2019			2018
Service cost	$	2,775		$	2,925		$	29		$	35
Interest cost		4,863			3,923			128			137
Expected return on plan assets		(11,300	)		(9,700	)		—			—
Amortization of net loss and prior service costs		2,430			1,326			(227	)		(149	)
Net periodic benefit cost (reduction of cost)	$	(1,232	)	$	(1,526	)	$	(70	)	$	23