Increase (Decrease) in Common Stock, Dividends, Declared as Percent

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[Line Items] for Schedule of Shareholders' Equity [Table]

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Stock Repurchase Program, Additional Authorized Amount

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Treasury Stock, Value, Acquired, Cost Method1

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- Definition

Aggregate dividends declared during the period for each share of common stock outstanding.

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Face amount or stated value per share of common stock.

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The maximum number of common shares permitted to be issued by an entity's charter and bylaws.

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The equity interest of noncontrolling shareholders, partners or other equity holders in consolidated entity.

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Face amount or stated value per share of preferred stock nonredeemable or redeemable solely at the option of the issuer.

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The maximum number of nonredeemable preferred shares (or preferred stock redeemable solely at the option of the issuer) permitted to be issued by an entity's charter and bylaws.

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Aggregate share number for all nonredeemable preferred stock (or preferred stock redeemable solely at the option of the issuer) held by stockholders. Does not include preferred shares that have been repurchased.

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Amount of cash inflow from a noncontrolling interest. Includes, but is not limited to, purchase of additional shares or other increase in noncontrolling interest ownership.

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As of the reporting date, the aggregate carrying amount of all noncontrolling interests which are redeemable by the (parent) entity (1) at a fixed or determinable price on a fixed or determinable date, (2) at the option of the holder of the noncontrolling interest, or (3) upon occurrence of an event that is not solely within the control of the (parent) entity. This item includes noncontrolling interest holder's ownership (or holders' ownership) regardless of the type of equity interest (common, preferred, other) including all potential organizational (legal) forms of the investee entity.

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Number of treasury shares or units reissued. Excludes reissuance of shares or units in treasury for award under share-based payment arrangement.

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Amount remaining of a stock repurchase plan authorized.

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Number of shares that have been repurchased during the period and are being held in treasury.

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Equity impact of the cost of common and preferred stock that were repurchased during the period. Recorded using the cost method.

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STOCKHOLDERS’ EQUITY AND REDEEMABLE NONCONTROLLING INTEREST (Narrative) (Details) - USD ($)	3 Months Ended													12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Feb. 22, 2021	Feb. 04, 2021	Jul. 01, 2015
Stockholders’ Equity and Redeemable Noncontrolling Interest [Line Items]
Preferred stock, par value		$ 1.00													$ 1.00
Preferred stock, shares outstanding		0													0
Common stock, par value		$ 0.01				$ 0.01									$ 0.01	$ 0.01
Common stock, shares authorized		600,000,000				600,000,000									600,000,000	600,000,000
Dividends per common share		$ 0.56	$ 0.56	$ 0.56	$ 0.56	$ 0.53	$ 0.53	$ 0.53	$ 0.53	$ 0.53	$ 0.50	$ 0.50	$ 0.50
Stock repurchase program, remaining authorized repurchase amount		$ 900,000,000													$ 900,000,000
Treasury stock value acquired cost method															$ 325,000,000	$ 350,000,000	$ 325,000,000
Reissuance of shares for employee benefit plan															3,000,000	2,000,000	3,000,000
Contributions from noncontrolling interest partners															$ 0	$ 0	$ 16,000,000
Redeemable noncontrolling interest		82,000,000				$ 76,000,000									82,000,000	76,000,000
UMass Joint Venture
Stockholders’ Equity and Redeemable Noncontrolling Interest [Line Items]
Ownership percentage by noncontrolling owners																				18.90%
Redeemable noncontrolling interest		$ 82,000,000				$ 76,000,000									$ 82,000,000	$ 76,000,000
Treasury Stock, at Cost
Stockholders’ Equity and Redeemable Noncontrolling Interest [Line Items]
Purchases of treasury stock, shares															2,700,000	3,500,000	3,400,000
Treasury stock value acquired cost method															$ 325,000,000	$ 350,000,000	$ 325,000,000
Treasury Stock, at Cost \| Accounts Payable and Accrued Liabilities
Stockholders’ Equity and Redeemable Noncontrolling Interest [Line Items]
Accrual										$ 3,000,000							$ 3,000,000
Forecast
Stockholders’ Equity and Redeemable Noncontrolling Interest [Line Items]
Dividends per common share	$ 0.62													$ 2.48
Subsequent Event
Stockholders’ Equity and Redeemable Noncontrolling Interest [Line Items]
Increase in quarterly dividends as percent																			10.70%
Additional authorized amount																		$ 1,000,000,000
Maximum
Stockholders’ Equity and Redeemable Noncontrolling Interest [Line Items]
Preferred stock, shares authorized		10,000,000													10,000,000