Pension and Other Postretirement Benefit Plans (Tables)

6 Months Ended

Sep. 30, 2020

Compensation And Retirement Disclosure [Abstract]

Schedule of Components of Net Periodic Benefit Cost (Income)

The components of net periodic benefit costs (income) for our postretirement benefit plans are shown in the following table:

	Pension Benefits
	Three Months Ended September 30,						Six Months Ended September 30,
	2020			2019 (1)			2020			2019 (1)
Components of net periodic benefit costs:
Service cost	$	383		$	600		$	760		$	1,181
Interest cost		16,100			17,427			32,186			36,089
Expected return on plan assets		(34,136	)		(35,500	)		(68,241	)		(70,618	)
Amortization of prior service credits		243			(233	)		485			(512	)
Amortization of net loss		7,807			6,808			15,605			13,019
Curtailment loss		—			23,476			—			23,476
Special termination benefits		—			11,642			—			11,642
Net periodic benefit income	$	(9,603	)	$	24,220		$	(19,205	)	$	14,277

(1) As adjusted; refer to Note 1.

	Other Postretirement Benefits
	Three Months Ended September 30,						Six Months Ended September 30,
	2020			2019 (1)			2020			2019 (1)
Components of net periodic benefit costs:
Service cost	$	—		$	18		$	—		$	62
Interest cost		28			614			56			1,478
Amortization of prior service credits		(1,276	)		(1,156	)		(2,552	)		(2,320	)
Amortization of gain		(1,191	)		(1,547	)		(2,382	)		(3,989	)
Curtailment gain		—			(49,491	)		—			(49,491	)
Net periodic benefit income	$	(2,439	)	$	(51,562	)	$	(4,878	)	$	(54,260	)

(1) As adjusted; refer to Note 1.