Equity Schedule of Stock by Class (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Jan. 01, 2018	Dec. 31, 2017	Dec. 31, 2015	Sep. 08, 2008	Jun. 04, 2008	May 22, 2008	May 19, 2008	Dec. 14, 2007	Nov. 21, 2007
Class of Stock [Line Items]
Senior preferred stock issued, shares	1,000,000			1,000,000
Senior preferred stock value	$ 117,149,000,000			$ 117,149,000,000
Senior preferred stock, shares outstanding	1,000,000			1,000,000
Preferred stock, shares issued	555,374,922			555,374,922
Preferred stock issued, amount	$ 19,130,000,000			$ 19,130,000,000
Preferred stock, shares outstanding	555,374,922			555,374,922
Preferred stock outstanding, amount	$ 19,130,000,000			$ 19,130,000,000
Series 2008-2 Senior Preferred Stock [Member]
Class of Stock [Line Items]
Senior preferred stock issued, shares	1,000,000			1,000,000
Senior preferred stock value	$ 117,149,000,000			$ 117,149,000,000	$ 1,000,000,000.0
Senior preferred stock, shares outstanding	1,000,000			1,000,000
Senior preferred stock, stated value per share	$ 117,149				$ 1,000
Series D Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock, shares issued	3,000,000			3,000,000
Preferred stock issued, amount	$ 150,000,000			$ 150,000,000
Preferred stock, shares outstanding	3,000,000			3,000,000
Preferred stock outstanding, amount	$ 150,000,000			$ 150,000,000
Preferred stock, stated value per share	$ 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	3,000,000			3,000,000
Preferred stock issued, amount	$ 150,000,000			$ 150,000,000
Preferred stock, shares outstanding	3,000,000			3,000,000
Preferred stock outstanding, amount	$ 150,000,000			$ 150,000,000
Preferred stock, stated value per share	$ 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	14,000,000			14,000,000
Preferred stock issued, amount	$ 690,000,000			$ 690,000,000
Preferred stock, shares outstanding	14,000,000			14,000,000
Preferred stock outstanding, amount	$ 690,000,000			$ 690,000,000
Preferred stock, stated value per share	$ 50
Preferred stock, annual dividend rate (as a percent)	0.73%
Preferred Stock, Redemption Terms	P2Y
Series G Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock, shares issued	6,000,000			6,000,000
Preferred stock issued, amount	$ 288,000,000			$ 288,000,000
Preferred stock, shares outstanding	6,000,000			6,000,000
Preferred stock outstanding, amount	$ 288,000,000			$ 288,000,000
Preferred stock, stated value per share	$ 50
Preferred stock, annual dividend rate (as a percent)	0.61%
Preferred Stock, Redemption Terms	P2Y
Series H Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock, shares issued	8,000,000			8,000,000
Preferred stock issued, amount	$ 400,000,000			$ 400,000,000
Preferred stock, shares outstanding	8,000,000			8,000,000
Preferred stock outstanding, amount	$ 400,000,000			$ 400,000,000
Preferred stock, stated value per share	$ 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	6,000,000			6,000,000
Preferred stock issued, amount	$ 300,000,000			$ 300,000,000
Preferred stock, shares outstanding	6,000,000			6,000,000
Preferred stock outstanding, amount	$ 300,000,000			$ 300,000,000
Preferred stock, stated value per share	$ 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	7,000,000			7,000,000
Preferred stock issued, amount	$ 345,000,000			$ 345,000,000
Preferred stock, shares outstanding	7,000,000			7,000,000
Preferred stock outstanding, amount	$ 345,000,000			$ 345,000,000
Preferred stock, stated value per share	$ 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	9,000,000			9,000,000
Preferred stock issued, amount	$ 460,000,000			$ 460,000,000
Preferred stock, shares outstanding	9,000,000			9,000,000
Preferred stock outstanding, amount	$ 460,000,000			$ 460,000,000
Preferred stock, stated value per share	$ 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	5,000,000			5,000,000
Preferred stock issued, amount	$ 225,000,000			$ 225,000,000
Preferred stock, shares outstanding	5,000,000			5,000,000
Preferred stock outstanding, amount	$ 225,000,000			$ 225,000,000
Preferred stock, stated value per share	$ 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	50,000,000			50,000,000
Preferred stock issued, amount	$ 2,500,000,000			$ 2,500,000,000
Preferred stock, shares outstanding	50,000,000			50,000,000
Preferred stock outstanding, amount	$ 2,500,000,000			$ 2,500,000,000
Preferred stock, stated value per share	$ 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	24,922			24,922
Preferred stock issued, amount	$ 2,492,000,000			$ 2,492,000,000
Preferred stock, shares outstanding	24,922			24,922
Preferred stock outstanding, amount	$ 2,492,000,000			$ 2,492,000,000
Preferred stock, stated value per share	$ 100,000
Preferred stock, annual dividend rate (as a percent)	5.375%
Series P Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock, shares issued	40,000,000			40,000,000
Preferred stock issued, amount	$ 1,000,000,000			$ 1,000,000,000
Preferred stock, shares outstanding	40,000,000			40,000,000
Preferred stock outstanding, amount	$ 1,000,000,000			$ 1,000,000,000
Preferred stock, stated value per share	$ 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	15,000,000			15,000,000
Preferred stock issued, amount	$ 375,000,000			$ 375,000,000
Preferred stock, shares outstanding	15,000,000			15,000,000
Preferred stock outstanding, amount	$ 375,000,000			$ 375,000,000
Preferred stock, stated value per share	$ 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	21,000,000			21,000,000					1,200,000	20,000,000
Preferred stock issued, amount	$ 530,000,000			$ 530,000,000					$ 30,000,000	$ 500,000,000
Preferred stock, shares outstanding	21,000,000			21,000,000
Preferred stock outstanding, amount	$ 530,000,000			$ 530,000,000
Preferred stock, stated value per share	$ 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	280,000,000			280,000,000
Preferred stock issued, amount	$ 7,000,000,000			$ 7,000,000,000
Preferred stock, shares outstanding	280,000,000			280,000,000
Preferred stock outstanding, amount	$ 7,000,000,000			$ 7,000,000,000
Preferred stock, stated value per share	$ 25
Preferred stock, annual dividend rate (as a percent)	7.75%
Preferred Stock, Redemption Terms	P5Y
Series T Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock, shares issued	89,000,000			89,000,000		1,000,000	8,000,000	80,000,000
Preferred stock issued, amount	$ 2,225,000,000			$ 2,225,000,000		$ 25,000,000	$ 200,000,000	$ 2,000,000,000
Preferred stock, shares outstanding	89,000,000			89,000,000
Preferred stock outstanding, amount	$ 2,225,000,000			$ 2,225,000,000
Preferred stock, stated value per share	$ 25
Preferred stock, annual dividend rate (as a percent)	8.25%
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%
Minimum [Member] | Series O Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock, annual dividend rate (as a percent)	7.00%
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	$ 1,200,000,000			$ 1,800,000,000
US Treasury [Member] | Scenario, Forecast [Member]
Class of Stock [Line Items]
Capital reserve amount for the fiscal year based on the amended Senior Preferred Stock Purchase agreement		$ 0	$ 600,000,000