Condensed Consolidated Statements of Stockholders' Equity Condensed Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) $ in Millions	Total	Preferred Stock	Common Stock [Member]	Treasury Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
Beginning Balance at Dec. 31, 2018		$ 0	$ 16	$ (1,717)	$ 17,346	$ (6,953)	$ 33
Beginning Balance (Shares Issued) at Dec. 31, 2018		0	1,632,148,030
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)						424
Total other comprehensive income (loss)							54
Stock-based compensation					28
Stock-based compensation (Shares)			6,001,343
Ending Balance at Mar. 31, 2019		$ 0	$ 16	(1,717)	17,374	(6,528)	87
Ending Balance (Shares Issued) at Mar. 31, 2019		0	1,638,149,373
Beginning Balance at Dec. 31, 2018		$ 0	$ 16	(1,717)	17,346	(6,953)	33
Beginning Balance (Shares Issued) at Dec. 31, 2018		0	1,632,148,030
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	$ 704
Total other comprehensive income (loss)	105
Ending Balance at Sep. 30, 2019		$ 0	$ 16	(1,717)	17,510	(6,249)	138
Ending Balance (Shares Issued) at Sep. 30, 2019		0	1,641,342,509
Beginning Balance at Mar. 31, 2019		$ 0	$ 16	(1,717)	17,374	(6,528)	87
Beginning Balance (Shares Issued) at Mar. 31, 2019		0	1,638,149,373
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)						154
Total other comprehensive income (loss)							(9)
Stock-based compensation					48
Stock-based compensation (Shares)			949,557
Ending Balance at Jun. 30, 2019		$ 0	$ 16	(1,717)	17,422	(6,375)	78
Ending Balance (Shares Issued) at Jun. 30, 2019		0	1,639,098,930
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	126					126
Total other comprehensive income (loss)	60						60
Stock-based compensation					89
Stock-based compensation (Shares)			2,243,579
Ending Balance at Sep. 30, 2019		$ 0	$ 16	(1,717)	17,510	(6,249)	138
Ending Balance (Shares Issued) at Sep. 30, 2019		0	1,641,342,509
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)						3,996
Total other comprehensive income (loss)							132
Stock-based compensation					50
Stock-based compensation (Shares)			1,146,402
Ending Balance at Dec. 31, 2019	13,877	$ 0	$ 16	(1,717)	17,561	(2,253)	270
Ending Balance (Shares Issued) at Dec. 31, 2019		0	1,642,488,911
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)						11
Cumulative effect adjustment for adoption of ASU 2016-13						(10)
Total other comprehensive income (loss)							(101)
Stock-based compensation					28
Stock-based compensation (Shares)			4,388,331
Ending Balance at Mar. 31, 2020		$ 0	$ 16	(1,717)	17,589	(2,252)	168
Ending Balance (Shares Issued) at Mar. 31, 2020		0	1,646,877,242
Beginning Balance at Dec. 31, 2019	13,877	$ 0	$ 16	(1,717)	17,561	(2,253)	270
Beginning Balance (Shares Issued) at Dec. 31, 2019		0	1,642,488,911
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(292)
Cumulative effect adjustment for adoption of ASU 2016-13	10
Total other comprehensive income (loss)	(119)
Ending Balance at Sep. 30, 2020	15,564	$ 0	$ 17	(1,717)	19,687	(2,574)	151
Ending Balance (Shares Issued) at Sep. 30, 2020		10,062,500	1,679,428,209
Beginning Balance at Mar. 31, 2020		$ 0	$ 16	(1,717)	17,589	(2,252)	168
Beginning Balance (Shares Issued) at Mar. 31, 2020		0	1,646,877,242
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)						(147)
Total other comprehensive income (loss)							(37)
Stock issuance (Par value)		$ 0	$ 0
Preferred stock issuance (Value in excess of par)					975
Common stock issuance (Value in excess of par)					975
Stock issuance (Shares)		10,062,500	29,382,500
Preferred stock dividends						(5)
Stock-based compensation					50
Stock-based compensation (Shares)			493,824
Ending Balance at Jun. 30, 2020		$ 0	$ 17	(1,717)	19,590	(2,405)	131
Ending Balance (Shares Issued) at Jun. 30, 2020		10,062,500	1,676,753,566
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(155)					(155)
Total other comprehensive income (loss)	20						20
Preferred stock dividends						(14)
Stock-based compensation					97
Stock-based compensation (Shares)			2,674,643
Ending Balance at Sep. 30, 2020	$ 15,564	$ 0	$ 17	$ (1,717)	$ 19,687	$ (2,574)	$ 151
Ending Balance (Shares Issued) at Sep. 30, 2020		10,062,500	1,679,428,209