Income Taxes Rate Reconciliation (Tables)

6 Months Ended

Mar. 31, 2020

Income Tax Disclosure [Abstract]

Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]

The reconciliation between the U.S. federal statutory income tax rate and the effective tax rate is presented below.

	Three months ended				Six months ended
	March 31,				March 31,
	2020		2019		2020		2019
U.S. federal statutory income tax rate	21.0	%	21.0	%	21.0	%	21.0	%
Adjustments to reconcile to the effective tax rate:
State income taxes, net of federal benefit	4.5		4.5		4.5		1.8
Excess tax (benefits) related to stock compensation	(0.5)		0.3		(0.8)		2.5
Tax credits	(1.5)		(1.3)		(1.4)		2.6
Global Intangible Low-taxed Income	(0.2)		0.5		—		(1.1)
Foreign income taxes	(0.5)		—		(0.6)		—
Valuation allowances	(0.6)		—		(0.6)		—
Other	—		1.4		0.4		(1.9)
	22.2	%	26.4	%	22.5	%	24.9	%
Walter Energy Accrual	—		—		—		(12.9)
Transition tax	—		—		—		4.7
Effective income tax rate	22.2	%	26.4	%	22.5	%	16.7	%