Pension and Retirement Benefits (Tables)

6 Months Ended

Mar. 31, 2021

Pension and Post-retirement Benefits

Schedule of components of net periodic pension and postretirement benefit cost

	Three Months Ended March 31,								Six Months Ended March 31,
	Pension Benefits				Other Benefits				Pension Benefits				Other Benefits
	2020		2021		2020		2021		2020		2021		2020		2021
Service cost	$	1,387	$	1,407	$	354	$	274	$	2,773	$	2,814	$	708	$	548
Interest cost		2,148		1,808		873		573		4,296		3,616		1,746		1,146
Expected return		(3,623)		(3,978)		—		—		(7,268)		(7,956)		—		—
Amortizations		1,859		1,956		462		—		3,718		3,912		924		—
Net periodic benefit cost	$	1,771	$	1,193	$	1,689	$	847	$	3,519	$	2,386	$	3,378	$	1,694