STATEMENT OF STOCKHOLDERS' EQUITY (Parenthetical) - shares shares in Millions	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement of Stockholders' Equity [Abstract]
Treasury Stock, Shares, Acquired	2.0	0.4	1.7

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

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
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-Section S99
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
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Name:	us-gaap_TreasuryStockSharesAcquired
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration