Income Taxes (Tables)

12 Months Ended

Dec. 31, 2018

Income Tax Disclosure [Abstract]

Earnings Before Income Taxes

Earnings before income taxes were derived from the following sources:

	2018		2017	2016
Domestic	$	905.0	809.4	739.4
Foreign	82.0		63.7	50.3
Earnings before income taxes	$	987.0	873.1	789.7

Components of Income Tax Expense (Benefit)

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

2018:	Current		Deferred	Total
Federal	$	143.8	27.4	171.2
State	38.8		0.2	39.0
Foreign	24.1		0.8	24.9
Income tax expense	$	206.7	28.4	235.1

2017:	Current		Deferred		Total
Federal	$	270.6	(33.1	)	237.5
State	33.2		3.3		36.5
Foreign	20.5		—		20.5
Income tax expense	$	324.3	(29.8	)	294.5

2016:	Current		Deferred	Total
Federal	$	223.9	23.2	247.1
State	28.2		1.2	29.4
Foreign	12.6		1.2	13.8
Income tax expense	$	264.7	25.6	290.3

Difference In Income Tax Expense And Expected Expense

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

	2018			2017		2016
U.S. federal statutory income tax rate	21.0		%	35.0	%	35.0	%
U.S. federal income tax expense at statutory rate	$	207.3		305.6		276.4
Increase (decrease) attributed to:
State income taxes, net of federal benefit	30.2			21.5		20.0
Transition tax	1.2			6.5		—
Remeasurement of deferred taxes for Tax Act	(11.5		)	(30.8	)	—
Other, net	7.9			(8.3	)	(6.1	)
Total income tax expense	$	235.1		294.5		290.3
Effective income tax rate	23.8		%	33.7	%	36.8	%

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:

	2018			2017
Deferred income tax assets (liabilities):
Inventory costing and valuation methods	$	4.2		3.6
Allowance for doubtful accounts	3.2			3.0
Insurance reserves	8.1			8.4
Customer promotions	1.9			1.3
Stock-based compensation	5.6			5.2
Federal and state benefit of uncertain tax positions	0.8			0.9
Foreign net operating loss and credit carryforwards	3.2			4.2
Foreign valuation allowances	(2.7		)	(2.8	)
Other, net	1.3			0.8
Total deferred income tax assets	25.6			24.6
Property and equipment	(104.7		)	(75.2	)
Total deferred income tax liabilities	(104.7		)	(75.2	)
Deferred income tax liabilities	$	(79.1	)	(50.6	)

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 was as follows:

	2018			2017
Balance at beginning of year:	$	4.4		5.4
Increase related to prior year tax positions	1.8			0.4
Decrease related to prior year tax positions	(0.6		)	(0.5	)
Increase related to current year tax positions	0.7			0.7
Decrease related to statute of limitation lapses	(0.9		)	(1.1	)
Settlements	(0.1		)	(0.5	)
Balance at end of year:	$	5.3		4.4