Share-Based Compensation (Full Value Share Award Activity) (Details 4) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of equity instruments other than options vested in period (in dollars)	$ 124	$ 107	$ 128
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Non-vested at beginning of the period (in shares)	1.2
Granted (in shares)	0.7
Deferred (in shares)	0.2
Vested (in shares)	(0.8)
Non-vested at end of the period (in shares)	1.3	1.2
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Weighted average grant-date fair value, non-vested at the beginning of the period (in dollars per share)	$ 133.40
Weighted average grant-date fair value, granted during the period (in dollars per share)	157.92
Weighted average grant-date fair value, deferred during the period (in dollars per share)	145.06
Weighted average grant-date fair value, vested during the period (in dollars per share)	141.02
Weighted average grant-date fair value, non-vested at the end of the period (in dollars per share)	144.10	$ 133.40
Advisor deferral plans [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Weighted average grant-date fair value, non-vested at the beginning of the period (in dollars per share)	136.81	144.37
Weighted average grant-date fair value, non-vested at the end of the period (in dollars per share)	$ 147.96	$ 136.81	$ 144.37