Goodwill and Other Intangible Assets (Changes in Carrying Amount of Goodwill) (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019
Goodwill [Roll Forward]
Goodwill, Beginning of Period	$ 20,624	$ 17,888
Acquisitions		2,828
Transfers		0
Foreign currency translation and other adjustments		(92)
Goodwill, End of Period	21,175	20,624
Goodwill, Before Change In Allocation
Goodwill [Roll Forward]
Acquisitions	204
Foreign currency translation and other adjustments	42
Goodwill, After Change In Allocation
Goodwill [Roll Forward]
Acquisitions	242
Foreign currency translation and other adjustments	63
Allocation in the fourth quarter of 2020	0
Google Inc.
Goodwill [Roll Forward]
Goodwill, Beginning of Period	19,921	17,521
Acquisitions		2,353
Transfers		9
Foreign currency translation and other adjustments		38
Goodwill, End of Period	0	19,921
Google Inc. \| Goodwill, Before Change In Allocation
Goodwill [Roll Forward]
Acquisitions	204
Foreign currency translation and other adjustments	46
Google Inc. \| Goodwill, After Change In Allocation
Goodwill [Roll Forward]
Acquisitions	0
Foreign currency translation and other adjustments	0
Allocation in the fourth quarter of 2020	(20,171)
Google Services
Goodwill [Roll Forward]
Goodwill, Beginning of Period	0	0
Acquisitions		0
Transfers		0
Foreign currency translation and other adjustments		0
Goodwill, End of Period	18,517	0
Google Services \| Goodwill, Before Change In Allocation
Goodwill [Roll Forward]
Acquisitions	0
Foreign currency translation and other adjustments	0
Google Services \| Goodwill, After Change In Allocation
Goodwill [Roll Forward]
Acquisitions	53
Foreign currency translation and other adjustments	56
Allocation in the fourth quarter of 2020	18,408
Google Cloud
Goodwill [Roll Forward]
Goodwill, Beginning of Period	0	0
Acquisitions		0
Transfers		0
Foreign currency translation and other adjustments		0
Goodwill, End of Period	1,957	0
Google Cloud \| Goodwill, Before Change In Allocation
Goodwill [Roll Forward]
Acquisitions	0
Foreign currency translation and other adjustments	0
Google Cloud \| Goodwill, After Change In Allocation
Goodwill [Roll Forward]
Acquisitions	189
Foreign currency translation and other adjustments	5
Allocation in the fourth quarter of 2020	1,763
Other Bets
Goodwill [Roll Forward]
Goodwill, Beginning of Period	703	367
Acquisitions		475
Transfers		(9)
Foreign currency translation and other adjustments		(130)
Goodwill, End of Period	701	$ 703
Other Bets \| Goodwill, Before Change In Allocation
Goodwill [Roll Forward]
Acquisitions	0
Foreign currency translation and other adjustments	(4)
Other Bets \| Goodwill, After Change In Allocation
Goodwill [Roll Forward]
Acquisitions	0
Foreign currency translation and other adjustments	2
Allocation in the fourth quarter of 2020	$ 0

Goodwill, Change In Goodwill Allocation

No definition available.

Name:	goog_GoodwillChangeInGoodwillAllocation
Namespace Prefix:	goog_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(10)(1))
-URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 45
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=120320667&loc=SL49117168-202975

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=99380562&loc=d3e13770-109266

+ Details

Name:	us-gaap_Goodwill
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of increase in asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized resulting from a business combination.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121556970&loc=d3e13816-109267

+ Details

Name:	us-gaap_GoodwillAcquiredDuringPeriod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

+ Details

Name:	us-gaap_GoodwillRollForward
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of transfers into (out 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.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (g)
-URI http://asc.fasb.org/extlink&oid=121556970&loc=d3e13816-109267

+ Details

Name:	us-gaap_GoodwillTransfers
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of increase (decrease) from foreign currency translation adjustments and purchase accounting adjustments of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 25
-Paragraph 16
-URI http://asc.fasb.org/extlink&oid=116868678&loc=d3e961-128460

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (g)
-URI http://asc.fasb.org/extlink&oid=121556970&loc=d3e13816-109267

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (f)
-URI http://asc.fasb.org/extlink&oid=121556970&loc=d3e13816-109267

+ Details

Name:	us-gaap_GoodwillTranslationAndPurchaseAccountingAdjustments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

Name:	goog_GoodwillChangeInGoodwillAllocationAxis=goog_GoodwillBeforeChangeInAllocationMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	goog_GoodwillChangeInGoodwillAllocationAxis=goog_GoodwillAfterChangeInAllocationMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=goog_GoogleInc.Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=goog_GoogleServicesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=goog_GoogleCloudMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=us-gaap_AllOtherSegmentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: