Shareholders' Equity - Schedule of Dividends Declared (Details) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended	3 Months Ended		9 Months Ended
	Oct. 31, 2018	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Dividends Payable [Line Items]
Preferred stock cash dividend		$ 55	$ 55	$ 146	$ 146
Common Stock Dividends Declared (in USD per share)		$ 0.47	$ 0.42	$ 1.31	$ 1.18
Common Stock Dividends		$ 179	$ 156	$ 486	$ 442
Series C Preferred Stock
Dividends Payable [Line Items]
Preferred dividends declared (USD per share)		$ 1,313	$ 1,313	$ 3,939	$ 3,939
Preferred stock cash dividend		$ 6	$ 6	$ 19	$ 19
Series C Preferred Stock, Depository Share
Dividends Payable [Line Items]
Preferred dividends declared (USD per share)		$ 0.33	$ 0.33	$ 0.99	$ 0.99
Series D Preferred Stock
Dividends Payable [Line Items]
Preferred dividends declared (USD per share)		$ 1,475	$ 1,475	$ 4,425	$ 4,425
Preferred stock cash dividend		$ 11	$ 11	$ 33	$ 33
Series D Preferred Stock, Depository Share
Dividends Payable [Line Items]
Preferred dividends declared (USD per share)		$ 0.37	$ 0.37	$ 1.11	$ 1.11
Series E Preferred Stock
Dividends Payable [Line Items]
Preferred dividends declared (USD per share)		$ 1,500	$ 1,500	$ 4,500	$ 4,500
Preferred stock cash dividend		$ 11	$ 11	$ 33	$ 33
Series E Preferred Stock, Depository Share
Dividends Payable [Line Items]
Preferred dividends declared (USD per share)		$ 0.38	$ 0.38	$ 1.14	$ 1.14
Series F Preferred Stock
Dividends Payable [Line Items]
Preferred dividends declared (USD per share)		$ 2,625	$ 2,625	$ 5,250	$ 5,250
Preferred stock cash dividend		$ 20	$ 20	$ 40	$ 40
Series F Preferred Stock, Depository Share
Dividends Payable [Line Items]
Preferred dividends declared (USD per share)		$ 26.25	$ 26.25	$ 52.5	$ 52.50
Series G Preferred Stock
Dividends Payable [Line Items]
Preferred dividends declared (USD per share)		$ 1,338	$ 1,338	$ 4,014	$ 4,014
Preferred stock cash dividend		$ 7	$ 7	$ 21	$ 21
Series G Preferred Stock, Depository Share
Dividends Payable [Line Items]
Preferred dividends declared (USD per share)		$ 0.33	$ 0.33	$ 0.99	$ 0.99
Subsequent Event | Series C Preferred Stock
Dividends Payable [Line Items]
Preferred dividends declared (USD per share)	$ 1,313,000,000
Preferred stock cash dividend	$ 7
Subsequent Event | Series C Preferred Stock, Depository Share
Dividends Payable [Line Items]
Preferred dividends declared (USD per share)	$ 330,000.00
Subsequent Event | Series D Preferred Stock
Dividends Payable [Line Items]
Preferred dividends declared (USD per share)	$ 1,475,000,000
Preferred stock cash dividend	$ 11
Subsequent Event | Series D Preferred Stock, Depository Share
Dividends Payable [Line Items]
Preferred dividends declared (USD per share)	$ 370,000.00
Subsequent Event | Series E Preferred Stock
Dividends Payable [Line Items]
Preferred dividends declared (USD per share)	$ 1,500,000,000
Preferred stock cash dividend	$ 11
Subsequent Event | Series E Preferred Stock, Depository Share
Dividends Payable [Line Items]
Preferred dividends declared (USD per share)	$ 380,000.00
Subsequent Event | Series G Preferred Stock
Dividends Payable [Line Items]
Preferred dividends declared (USD per share)	$ 1,338,000,000
Preferred stock cash dividend	$ 7
Subsequent Event | Series G Preferred Stock, Depository Share
Dividends Payable [Line Items]
Preferred dividends declared (USD per share)	$ 330,000.00
Subsequent Event | Series H Preferred Stock
Dividends Payable [Line Items]
Preferred dividends declared (USD per share)	$ 1,219,000,000
Preferred stock cash dividend	$ 6
Subsequent Event | Series H Preferred Stock, Depository Share
Dividends Payable [Line Items]
Preferred dividends declared (USD per share)	$ 12,190,000.00