Deferred rent and Lease incentives

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Maturity period of short term investment maximum.

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Net holding gains (losses) on equity securities in net earnings on securities that were still owned. All equity securities other than those accounted for under the equity method are carried at fair value through net earnings.

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No definition available.

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Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

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Amount of equity securities categorized neither as held-to-maturity nor as trading.

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Amount after tax of increase (decrease) to equity or (increase) decrease to net assets, resulting from the cumulative effect adjustment of a new accounting principle applied in the period of adoption.

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Additional shares included in the calculation of diluted EPS as a result of the potentially dilutive effect of share based payment arrangements using the treasury stock method.

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Present value of lessee's discounted obligation for lease payments from operating lease.

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Amount of lessee's right to use underlying asset under operating lease.

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Amount of increase (decrease) in accumulated other comprehensive income (AOCI) for reclassification to retained earnings of tax effect from remeasurement of deferred tax pursuant to Tax Cuts and Jobs Act.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Accounting Policies - Narrative (Details) - USD ($) $ in Millions		1 Months Ended	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jan. 01, 2019	Jan. 01, 2018
Significant Accounting Policies [Line Items]
Cumulative effect of accounting change							$ 4
Operating lease liability			$ 180			$ 198
Operating lease right-of-use asset			158			174
Deferred rent and lease incentives			$ 22			$ 24
Tax Cuts and Jobs Act, reclassification from AOCI to retained earnings, tax effect					$ 0
Weighted average common shares adjustment related to stock-based compensation			1,100,000	1,600,000	2,000,000.0
Anti-dilutive potential common shares related to stock-based compensation plans			0	0	0
Maturities of short term investments			3 months
Equity securities
Significant Accounting Policies [Line Items]
Available-for-sale securities, Equity securities	$ 1,600	$ 1,600			$ 1,600
Equity securities \| Accounting Standards Update 2016-01
Significant Accounting Policies [Line Items]
Cumulative effect of accounting change							(221)
Tax Cuts and Jobs Act of 2017 \| Accounting Standards Update 2018-02
Significant Accounting Policies [Line Items]
Tax Cuts and Jobs Act, reclassification from AOCI to retained earnings, tax effect	$ 145	$ 145
Limited partnerships and similar investments \| Accounting Standards Update 2016-01
Significant Accounting Policies [Line Items]
Cumulative effect of accounting change							$ (4)
Equity securities still owned \| Equity securities \| Accounting Standards Update 2016-01
Significant Accounting Policies [Line Items]
Net holding gains (losses) on equity securities			$ 207	$ (257)