Equity Schedule of Stock by Class (Details)		12 Months Ended
	Sep. 08, 2008 USD ($) $ / shares shares	Dec. 31, 2020 USD ($) $ / shares shares	Dec. 31, 2019 USD ($) shares	Dec. 31, 2018 USD ($) shares	Mar. 31, 2021 shares	Sep. 30, 2020 USD ($)	Dec. 31, 2017 USD ($) shares	Jun. 04, 2008 USD ($) shares	May 22, 2008 USD ($) shares	May 19, 2008 USD ($) shares	Dec. 14, 2007 USD ($) shares	Nov. 21, 2007 USD ($) shares
Class of Stock [Line Items]
Senior preferred stock value		$ 120,836,000,000	$ 120,836,000,000
Senior preferred stock, shares outstanding | shares		142,192,000,000	131,178,000,000
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest		$ 25,259,000,000	$ 14,608,000,000	$ 6,240,000,000			$ (3,686,000,000)
Preferred stock, shares issued | shares		555,374,922
Preferred Stock, Value, Issued		$ 19,130,000,000	$ 19,130,000,000
Preferred stock, shares outstanding | shares		555,374,922	555,374,922
Common Stock, Shares, Outstanding | shares		1,158,087,567	1,158,087,567
Weighted Average Number of Shares, Contingently Issuable | shares		4,700,000,000	4,600,000,000	4,600,000,000
Preferred Stock, Redemption Terms		two
Payment Of Cash Dividends On Senior Preferred Stock To Treasury		$ 0	$ 5,601,000,000	$ 9,372,000,000
Forecast [Member]
Class of Stock [Line Items]
Senior preferred stock, shares outstanding | shares					146,800,000,000
Series 2008-2 Senior Preferred Stock [Member]
Class of Stock [Line Items]
Senior preferred stock value		$ 120,836,000,000	$ 120,836,000,000
Senior preferred stock issued, shares | shares			1,000,000
Senior preferred stock, stated value per share | $ / shares	$ 1,000	$ 120,836
Aggregate liquidation preference of senior preferred stock	$ 1,000,000,000.0
Stock Issued During Period, Shares, New Issues | shares	1,000,000
Series D Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock, shares issued | shares		3,000,000	3,000,000
Preferred Stock, Value, Issued		$ 150,000,000	$ 150,000,000
Preferred stock, stated value per share | $ / shares		$ 50
Preferred stock, annual dividend rate (as a percent)		5.25%
Series E Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock, shares issued | shares		3,000,000	3,000,000
Preferred Stock, Value, Issued		$ 150,000,000	$ 150,000,000
Preferred stock, stated value per share | $ / shares		$ 50
Preferred stock, annual dividend rate (as a percent)		5.10%
Series F Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock, shares issued | shares		14,000,000	14,000,000
Preferred Stock, Value, Issued		$ 690,000,000	$ 690,000,000
Preferred stock, stated value per share | $ / shares		$ 50
Preferred stock, annual dividend rate (as a percent)		0.15%
Series G Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock, shares issued | shares		6,000,000	6,000,000
Preferred Stock, Value, Issued		$ 288,000,000	$ 288,000,000
Preferred stock, stated value per share | $ / shares		$ 50
Preferred stock, annual dividend rate (as a percent)		0.00%
Series H Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock, shares issued | shares		8,000,000	8,000,000
Preferred Stock, Value, Issued		$ 400,000,000	$ 400,000,000
Preferred stock, stated value per share | $ / shares		$ 50
Preferred stock, annual dividend rate (as a percent)		5.81%
Series I Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock, shares issued | shares		6,000,000	6,000,000
Preferred Stock, Value, Issued		$ 300,000,000	$ 300,000,000
Preferred stock, stated value per share | $ / shares		$ 50
Preferred stock, annual dividend rate (as a percent)		5.375%
Series L Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock, shares issued | shares		7,000,000	7,000,000
Preferred Stock, Value, Issued		$ 345,000,000	$ 345,000,000
Preferred stock, stated value per share | $ / shares		$ 50
Preferred stock, annual dividend rate (as a percent)		5.125%
Series M Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock, shares issued | shares		9,000,000	9,000,000
Preferred Stock, Value, Issued		$ 460,000,000	$ 460,000,000
Preferred stock, stated value per share | $ / shares		$ 50
Preferred stock, annual dividend rate (as a percent)		4.75%
Series N Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock, shares issued | shares		5,000,000	5,000,000
Preferred Stock, Value, Issued		$ 225,000,000	$ 225,000,000
Preferred stock, stated value per share | $ / shares		$ 50
Preferred stock, annual dividend rate (as a percent)		5.50%
Series O Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock, shares issued | shares		50,000,000	50,000,000
Preferred Stock, Value, Issued		$ 2,500,000,000	$ 2,500,000,000
Preferred stock, stated value per share | $ / shares		$ 50
Preferred stock, annual dividend rate (as a percent)		7.00%
Convertible Series 2004-1 Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock, shares issued | shares		24,922	24,922
Preferred Stock, Value, Issued		$ 2,492,000,000	$ 2,492,000,000
Preferred stock, shares outstanding | shares		24,922	24,922
Preferred stock, stated value per share | $ / shares		$ 100,000
Preferred stock, annual dividend rate (as a percent)		5.375%
Convertible Stock, Conversion Price | $ / shares		$ 94.31
Conversion Stock, Conversion Rate		1,060.3329
Preferred Stock, Redemption Price Per Share | $ / shares		$ 105,000
Series P Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock, shares issued | shares		40,000,000	40,000,000
Preferred Stock, Value, Issued		$ 1,000,000,000	$ 1,000,000,000
Preferred stock, stated value per share | $ / shares		$ 25
Preferred stock, annual dividend rate (as a percent)		4.50%
Series Q Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock, shares issued | shares		15,000,000	15,000,000
Preferred Stock, Value, Issued		$ 375,000,000	$ 375,000,000
Preferred stock, stated value per share | $ / shares		$ 25
Preferred stock, annual dividend rate (as a percent)		6.75%
Series R Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock, shares issued | shares		21,000,000	21,000,000								1,200,000	20,000,000
Preferred Stock, Value, Issued		$ 530,000,000	$ 530,000,000								$ 30,000,000	$ 500,000,000
Preferred stock, stated value per share | $ / shares		$ 25
Preferred stock, annual dividend rate (as a percent)		7.625%
Series S Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock, shares issued | shares		280,000,000	280,000,000
Preferred Stock, Value, Issued		$ 7,000,000,000	$ 7,000,000,000
Preferred stock, stated value per share | $ / shares		$ 25
Preferred stock, annual dividend rate (as a percent)		7.75%
Series T Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock, shares issued | shares		89,000,000	89,000,000					1,000,000	8,000,000	80,000,000
Preferred Stock, Value, Issued		$ 2,225,000,000	$ 2,225,000,000						$ 200,000,000	$ 2,000,000,000.0
Preferred stock, stated value per share | $ / shares		$ 25
Preferred stock, annual dividend rate (as a percent)		8.25%
Preferred Stock, Liquidation Preference, Value								$ 25,000,000
Maximum [Member] | Series F Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock, annual dividend rate (as a percent)		11.00%
Maximum [Member] | Series G Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock, annual dividend rate (as a percent)		11.00%
Maximum [Member] | Series O Preferred Stock [Member]
Class of Stock [Line Items]
Preferred Stock, Redemption Price Per Share | $ / shares		$ 52.50
Minimum [Member] | Series O Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock, annual dividend rate (as a percent)		7.00%
Preferred Stock, Redemption Price Per Share | $ / shares		$ 50
Minimum [Member] | Series P Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock, annual dividend rate (as a percent)		4.50%
Minimum [Member] | Series S Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock, annual dividend rate (as a percent)		7.75%
Two-year Constant Maturity U.S. Treasury Rate [Member] | Series F Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock dividend rate, basis spread on variable rate		0.16%
Two-year Constant Maturity U.S. Treasury Rate [Member] | Series G Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock dividend rate, basis spread on variable rate		0.18%
Ten-year Constant Maturity U.S. Treasury Rate [Member] | Series O Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock dividend rate, basis spread on variable rate		2.375%
Three-Month LIBOR [Member] | Series P Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock dividend rate, basis spread on variable rate		0.75%
Three-Month LIBOR [Member] | Series S Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock dividend rate, basis spread on variable rate		4.23%
US Treasury [Member]
Class of Stock [Line Items]
Capital reserve amount for the fiscal year based on the amended Senior Preferred Stock Purchase agreement			$ 3,000,000,000			$ 25,000,000,000	$ 3,000,000,000
Aggregate liquidation preference of senior preferred stock		$ 142,200,000,000
Senior Preferred Stock
Class of Stock [Line Items]
Shares, Outstanding | shares		1,000,000	1,000,000	1,000,000			1,000,000
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest		$ 120,836,000,000	$ 120,836,000,000	$ 120,836,000,000			$ 117,149,000,000
Accumulated Deficit
Class of Stock [Line Items]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest		$ (108,110,000,000)	(118,776,000,000)	(127,335,000,000)			$ (133,805,000,000)
Payment Of Cash Dividends On Senior Preferred Stock To Treasury			$ 5,601,000,000	$ 9,372,000,000
Preferred Stock
Class of Stock [Line Items]
Shares, Outstanding | shares		556,000,000	556,000,000	556,000,000			556,000,000
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest		$ 19,130,000,000	$ 19,130,000,000	$ 19,130,000,000			$ 19,130,000,000
Preferred stock, shares issued | shares		556,000,000	556,000,000