Benefit Plans Schedule of Net Benefit Costs (Tables)

6 Months Ended

Feb. 28, 2021

Retirement Benefits [Abstract]

Schedule of Net Benefit Costs of Assumptions Used

Components of net periodic benefit costs for the three and six months ended February 28, 2021, and February 29, 2020, are as follows:

	Three Months Ended
	Qualified Pension Benefits				Nonqualified Pension Benefits				Other Benefits
	February 28, 2021		February 29, 2020		February 28, 2021		February 29, 2020		February 28, 2021		February 29, 2020
Components of net periodic benefit costs:	(Dollars in thousands)
Service cost	$	11,307	$	10,538	$	108	$	101	$	297	$	262
Interest cost	4,141		5,431		68		107		123		187
Expected return on assets	(10,910)		(11,671)		—		—		—		—
Prior service cost (credit) amortization	45		45		(28)		(28)		(111)		(111)
Actuarial loss (gain) amortization	5,447		5,396		53		25		(341)		(348)
Net periodic benefit cost (benefit)	$	10,030	$	9,739	$	201	$	205	$	(32)	$	(10)
	Six Months Ended
	Qualified Pension Benefits				Nonqualified Pension Benefits				Other Benefits
	February 28, 2021		February 29, 2020		February 28, 2021		February 29, 2020		February 28, 2021		February 29, 2020
Components of net periodic benefit costs:	(Dollars in thousands)
Service cost	$	22,614	$	21,076	$	217	$	203	$	593	$	525
Interest cost	8,281		10,861		136		214		246		374
Expected return on assets	(21,821)		(23,342)		—		—		—		—
Prior service cost (credit) amortization	89		89		(57)		(57)		(223)		(223)
Actuarial loss (gain) amortization	10,895		10,791		106		49		(682)		(696)
Net periodic benefit cost (benefit)	$	20,058	$	19,475	$	402	$	409	$	(66)	$	(20)