EPS - Calculation of EPS and the Reconciliation of Earnings Per Share to Earnings Per Diluted Share (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Earnings per share:
Net income (loss) available to common shareholders	$ 530	$ 421	$ 1,718	$ 1,685
Less: Income allocated to participating securities	4	4	16	18
Earnings per share - basic	526	417	1,702	1,667
Earnings per diluted share:
Net income available to common shareholders	530	421	1,718	1,685
Stock-based awards	0	0	0	0
Net income available to common shareholders plus assumed conversions	530	421	1,718	1,685
Less: Income allocated to participating securities	4	4	16	18
Net income allocated to common shareholders	$ 526	$ 417	$ 1,702	$ 1,667
Earnings per share:
Net income allocated to common shareholders	726,715,542	667,624,132	708,848,535	680,181,785
Effect of dilutive securities:
Stock-based awards	9,000,000	11,000,000	9,000,000	13,000,000
Net income allocated to common shareholders	736,086,399	679,198,715	718,413,237	693,078,647
Earnings per share:
Earnings per share - basic	$ 0.72	$ 0.62	$ 2.40	$ 2.45
Earnings per diluted share:
Earnings per share - diluted	$ 0.71	$ 0.61	$ 2.37	$ 2.41