Income Taxes (Tables)

12 Months Ended

Dec. 31, 2023

Income Tax Disclosure [Abstract]

Earnings Before Income Taxes

Earnings before income taxes were derived from the following sources:

	2023		2022	2021
Domestic	$	1,392.7	1,335.7	1,100.3
Foreign	129.3		104.3	107.5
Earnings before income taxes	$	1,522.0	1,440.0	1,207.8

Components of Income Tax Expense (Benefit)

Components of income tax expense (benefit) were as follows:

	2023				2022			2021
	Current		Deferred	Total	Current	Deferred	Total	Current	Deferred	Total
Federal	$	273.3	(9.2)	264.1	267.6	(5.0)	262.6	214.3	(11.4)	202.9
State	59.6		(1.3)	58.3	58.0	(1.1)	56.9	46.7	(1.7)	45.0
Foreign	44.9		(0.3)	44.6	35.0	(1.4)	33.6	34.1	0.8	34.9
Income tax expense	$	377.8	(10.8)	367.0	360.6	(7.5)	353.1	295.1	(12.3)	282.8

Difference In Income Tax Expense And Expected Expense

Income tax expense in the accompanying consolidated financial statements differed from the expected expense as follows:

	2023				2022				2021
	Amount		Percent		Amount		Percent		Amount		Percent
U.S. federal statutory income tax	$	319.6	21.0	%	$	302.4	21.0	%	$	253.6	21.0	%
State income taxes, net of federal benefit	$	45.1	3.0	%	$	45.6	3.2	%	$	34.9	2.9	%
Other, net	$	2.3	0.1	%	$	5.1	0.3	%	$	(5.7)	-0.5	%
Effective income tax rate	$	367.0	24.1	%	$	353.1	24.5	%	$	282.8	23.4	%

Summary of Temporary Differences That Give Rise to Deferred Income Tax Assets And Liabilities

The tax effects of temporary differences that give rise to deferred income tax assets and liabilities at year end consisted of the following: 

	2023		2022
Deferred income tax assets:
Inventory costing and valuation methods	$	5.6	6.7
Insurance reserves	8.3		8.6
Foreign net operating loss and credit carryforwards	3.0		2.6
Stock-based compensation	3.8		3.6
Operating lease liabilities	69.5		62.6
Section 174 capitalization	7.4		3.4
Other, deferred tax assets	9.4		9.6
Total deferred income tax assets	107.0		97.1
Less: Valuation allowances	(2.2)		(1.8)
Total net deferred income tax assets	104.8		95.3
Property and equipment	(95.4)		(102.6)
Operating lease ROU assets	(68.3)		(61.5)
Prepaid expenses	(3.5)		(3.5)
Other, deferred tax liabilities	(0.4)		(1.3)
Total deferred income tax liabilities	(167.6)		(168.9)
Net deferred income tax liabilities	$	(62.8)	(73.6)

Reconciliation of The Beginning and Ending Amount of Total Gross Unrecognized Tax Benefits

A reconciliation of the beginning and ending amount of total gross unrecognized tax benefits is as follows:

	2023		2022
Balance at beginning of year:	$	10.1	7.4
Increase related to prior year tax positions	5.6		3.5
Increase related to current year tax positions	0.6		0.6
Decrease related to statute of limitation lapses	(6.1)		(0.9)
Settlements	—		(0.5)
Balance at end of year:	$	10.2	10.1