Subsequent Events	12 Months Ended
Dec. 31, 2020
Subsequent Events [Abstract]
Subsequent Events	Subsequent EventIn January 2021, Cruise Holdings issued Class G Preferred Shares in exchange for $2.2 billion from Microsoft and other investors, including $1.0 billion from General Motors Holdings LLC. As a result, Cruise Holdings has fallen below the ownership threshold required for inclusion in our U.S. consolidated income tax returns. In the three months ended March 31, 2021, we will establish a valuation allowance of approximately $350 million against deferred tax assets that may not be realizable. In addition, we, Cruise Holdings and Microsoft entered into a long-term strategic relationship to accelerate the commercialization of self-driving vehicles with Microsoft being the preferred cloud provider.

The entire disclosure for significant events or transactions that occurred after the balance sheet date through the date the financial statements were issued or the date the financial statements were available to be issued. Examples include: the sale of a capital stock issue, purchase of a business, settlement of litigation, catastrophic loss, significant foreign exchange rate changes, loans to insiders or affiliates, and transactions not in the ordinary course of business.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 855
-URI http://asc.fasb.org/topic&trid=2122774

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 855
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=6842918&loc=SL6314017-165662

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