Number Of Days Notice Required To Cancel Health Insurance Contract

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Percentage of average payout, after reinsurance, in the first 90 days after a claim is incurred, beginning with the earliest accident year disclosed for short-duration insurance contracts.

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Sum of the carrying values as of the balance sheet date of obligations incurred through that date and due within one year (or the operating cycle, if longer), including liabilities incurred (and for which invoices have typically been received) and payable to vendors for goods and services received, taxes, interest, rent and utilities, accrued salaries and bonuses, payroll taxes and fringe benefits.

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Amount due from customers or clients, within one year of the balance sheet date (or the normal operating cycle, whichever is longer), for goods or services (including trade receivables) that have been delivered or sold in the normal course of business, reduced to the estimated net realizable fair value by an allowance established by the entity of the amount it deems uncertain of collection.

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The amount of money in accounts that may bear interest and that the depositor is entitled to withdraw at any time without prior notice.

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Amount of loss from the write-down of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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The amount of impairment loss recognized in the period resulting from the write-down of the carrying amount of an intangible asset (excluding goodwill) to fair value.

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Amount of cumulative effect of the change in accounting principle or new accounting pronouncement on retained earnings or other components of equity or net assets in the statement of financial position as of the beginning of the earliest period presented.

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Description of the transition method used when a new accounting pronouncement or a change in accounting principle is adopted.

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A description of the fact that the effect (or portion of the effect) of initially applying the pending content is not significant or not practicable to estimate.

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Amount of liabilities classified as other, due within one year or the normal operating cycle, if longer.

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Amount, after allowance, of receivables classified as other, due within one year or the operating cycle, if longer.

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Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Discount rate from fair value on offering date that participants pay for shares.

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Period from grant date that an equity-based award expires, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Basis of Presentation, Uses of Estimates and Significant Accounting Policies (Details) $ in Millions	12 Months Ended
	Dec. 31, 2018 USD ($)	Jan. 01, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2015 USD ($)
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets		$ 24	$ 0	$ 28
Accounts payable and accrued liabilities	$ 16,705		15,180
Other current receivables	6,862		6,262
Goodwill, Impairment Loss	0
Impairment of Intangible Assets (Excluding Goodwill)	$ 0
Number Of Days Notice Required To Cancel Health Insurance Contract	30 days
Accounts Receivable, Net, Current	$ 11,388		9,568
Other Liabilities, Current	12,244		12,286
Other Current Liabilities [Member]
Health savings account deposits	$ 7,500		6,400
Restricted Stock [Member] \| Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	2 years
Restricted Stock [Member] \| Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	5 years
Stock Options and SARs [Member] [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	4 years
Share-based Compensation Arrangement by Share-based Payment Plan Award, Options, Award Exercisable Period	10 years
Employee Stock Purchase Plan (ESPP) [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Discount from Market Price, Offering Date	85.00%
Accounting Standards Update 2016-02 [Member]
New Accounting Pronouncement or Change in Accounting Principle, Description of Transition Method	Cumulative effect upon adoption approach
New Accounting Pronouncement, Transition Guidance Not Significant or Not Practical	Impact is not material
Accounting Standards Update 2016-01 [Member]
New Accounting Pronouncement or Change in Accounting Principle, Description of Transition Method	Prospective
Health Insurance Product Line [Member]
Short-duration Insurance Contracts, Historical Claims Duration, First 90 Days	0.9
Products and services [Member]
Accounts Receivable, Net, Current	$ 3,900		3,700
Pharmaceutical Manufacturer Rebates Receivable [Member]
Other current receivables	$ 4,200		$ 3,800