Income Taxes (Tables)

12 Months Ended

Dec. 31, 2017

Income Tax Disclosure [Abstract]

Schedule of deferred tax assets and liabilities

	December 31,
	2017			2016
Deferred tax assets:
Allowance for doubtful accounts	$	1,885		$	2,686
Tax credits	7,179			9,363
Other accruals	97,247			153,955
Net operating losses	346			304
Other	14,784			19,870
Total deferred tax assets	121,441			186,178
Deferred tax liabilities:
Inventories	55,965			76,694
Property and equipment	122,354			157,228
Other	28,528			42,422
Total deferred tax liabilities	206,847			276,344
Net deferred tax liabilities	$	(85,406	)	$	(90,166	)

Schedule of components of the provision for income taxes

	For the Year Ended   December 31, 2017
	Current		Deferred			Total
Federal income tax expense (benefit)	$	467,577	$	(13,053	)	$	454,524
State income tax expense	41,183		8,293			49,476
Net income tax expense (benefit)	$	508,760	$	(4,760	)	$	504,000

	For the Year Ended   December 31, 2016
	Current		Deferred		Total
Federal income tax expense	$	540,090	$	7,558	$	547,648
State income tax expense	49,016		2,836		51,852
Net income tax expense	$	589,106	$	10,394	$	599,500

	For the Year Ended   December 31, 2015
	Current		Deferred			Total
Federal income tax expense (benefit)	$	504,558	$	(21,973	)	$	482,585
State income tax expense (benefit)	47,242		(677		)	46,565
Net income tax expense (benefit)	$	551,800	$	(22,650	)	$	529,150

Reconciliation of the provision for income taxes to the amounts computed at the federal statutory rate

	For the Year Ended   December 31,
	2017			2016			2015
Federal income taxes at statutory rate	$	573,231		$	573,020		$	511,128
State income taxes, net of federal tax benefit	39,062			35,285			32,137
Excess tax benefit from share-based compensation	(48,688		)	—			—
Revaluation of deferred tax liability	(53,240		)	—			—
Other items, net	(6,365		)	(8,805		)	(14,115		)
Total provision for income taxes	$	504,000		$	599,500		$	529,150

Summary of changes in gross amount of unrecognized tax benefits, excluding interest and penalties

	2017			2016			2015
Unrealized tax benefit, balance at January 1,	$	34,798		$	36,928		$	49,598
Additions based on tax positions related to the current year	6,299			6,116			5,405
Additions based on tax positions related to prior years	—			—			995
Payments related to items settled with taxing authorities	—			(195		)	(4,012		)
Reductions due to the lapse of statute of limitations and settlements	(5,709		)	(8,051		)	(15,058		)
Unrealized tax benefit, balance at December 31,	$	35,388		$	34,798		$	36,928