Income Taxes - Income Taxes (Detail)	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Statutory Federal Tax Rate	21.00%	21.00%	21.00%
Tax Exempt Income	(0.90%)	(0.60%)	(0.40%)
Foreign Tax Rate Differential	0.70%	0.20%	(0.40%)
Excess Tax Benefit Related to Share-Based Compensation	(0.60%)	(0.90%)	(0.90%)
Tax Credits	(1.70%)	(1.00%)	(1.10%)
Reversal of Tax Benefits Previously Recognized through Earnings	1.60%	0.00%	0.00%
State Taxes, net	3.20%	2.80%	3.40%
Impact of Tax Cuts and Jobs Act	0	0	(0.002)
Change in Accounting Method	0.00%	0.00%	(1.20%)
Valuation Allowance	1.60%	1.50%	0.00%
Other	0.80%	0.20%	0.30%
Effective Tax Rate	25.70%	23.20%	20.50%

Effective Income Tax Rate Reconciliation, Effect of Change in Accounting Method, Percent

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Income Tax Reconciliation, Leveraged Lease Adjustments

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Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 12
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Percentage of domestic federal statutory tax rate applicable to pretax income (loss).

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section S99
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Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to changes in the valuation allowance for deferred tax assets.

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Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 6.I.Fact.4)
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Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations applicable to statutory income tax expense (benefit) outside of the country of domicile.

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Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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-SubTopic 10
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Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to revisions of previously reported income tax expense.

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Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations applicable to state and local income tax expense (benefit), net of federal tax expense (benefit).

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Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to tax credits. Including, but not limited to, research credit, foreign tax credit, investment tax credit, and other tax credits.

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Percentage of reported income tax expense (benefit) in excess of (less than) expected income tax expense (benefit) computed by applying domestic federal statutory income tax rate to pretax income (loss) from continuing operations, attributable to Tax Cuts and Jobs Act.

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