Stockholders' Equity and Noncontrolling Interests - Preferred and Common Stock (Details) - USD ($) $ in Millions	1 Months Ended
	May 31, 2019	Jun. 30, 2020	Dec. 31, 2019
Stockholders' Equity Note [Abstract]
Preferred stock shares authorized (in shares)		2,000,000,000.0	2,000,000,000.0
Common stock shares authorized (in shares)		5,000,000,000.0	5,000,000,000.0
Preferred stock shares outstanding (in shares)		0	0
Common stock shares issued (in shares)		1,400,000,000	1,400,000,000
Common stock shares outstanding (in shares)		1,400,000,000	1,400,000,000
Series F Preferred Stock [Member] | GM Cruise Holdings LLC [Member]
Class of Stock [Line Items]
Proceeds from issuance of preferred stock	$ 1,100
Investment in subsidiaries	$ 687