Employee Incentive Plans - Status of and Changes in Restricted Stock Awards and SPSs (Details) - $ / shares shares in Thousands	12 Months Ended
Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Restricted Stock Grants and Units
Grants/Units
Outstanding - January 1 (in shares)	1,535	1,524	1,600
Awarded (in shares)	700	876	899
Vested (in shares)	(759)	(714)	(866)
Forfeited (in shares)	(72)	(151)	(109)
Outstanding - December 31 (in shares)	1,404	1,535	1,524
Weighted Average Fair Value at Award Date
Outstanding - January 1 (in dollars per share)	$ 219.25	$ 202.85	$ 186.12
Awarded (in dollars per share)	294.60	229.60	213.82
Vested (in dollars per share)	214.70	197.83	184.07
Forfeited (in dollars per share)	256.24	215.02	197.01
Outstanding - December 31 (in dollars per share)	$ 257.38	$ 219.25	$ 202.85
SPSs
Grants/Units
Outstanding - January 1 (in shares)	780	860	808
Awarded (in shares)	219	294	331
Vested (in shares)	(250)	(261)	(206)
Forfeited (in shares)	(63)	(113)	(73)
Outstanding - December 31 (in shares)	686	780	860
Weighted Average Fair Value at Award Date
Outstanding - January 1 (in dollars per share)	$ 212.68	$ 197.07	$ 190.02
Awarded (in dollars per share)	293.85	230.69	213.90
Vested (in dollars per share)	191.78	183.60	196.29
Forfeited (in dollars per share)	237.50	207.75	197.38
Outstanding - December 31 (in dollars per share)	$ 243.90	$ 212.68	$ 197.07

The number of equity-based payment instruments, excluding stock (or unit) options, that were forfeited during the reporting period.

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Weighted average fair value as of the grant date of equity-based award plans other than stock (unit) option plans that were not exercised or put into effect as a result of the occurrence of a terminating event.

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The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(i)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(ii)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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Per share or unit weighted-average fair value of nonvested award under share-based payment arrangement. Excludes share and unit options.

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The number of equity-based payment instruments, excluding stock (or unit) options, that vested during the reporting period.

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The weighted average fair value as of grant date pertaining to an equity-based award plan other than a stock (or unit) option plan for which the grantee gained the right during the reporting period, by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash in accordance with the terms of the arrangement.

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