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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-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21463-112644

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
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Name:	us-gaap_TreasuryStockSharesAcquired
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

Contingencies and Certain Commitments (Details) - USD ($) shares in Millions, $ in Billions	Feb. 12, 2019	Feb. 07, 2019	Mar. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Share repurchase agreement, amount		$ 6.8
Accelerated share repurchases, cash paid	$ 6.8
Shares repurchased	130
Accelerated share repurchases, shares repurchased during period, percentage of agreement amount		80.00%
Remaining authorized repurchase amount			$ 5.3