Compensation Plans (401k Plans and Performance Fees) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2020 USD ($) plan	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Share-based Payment Arrangement [Abstract]
Number of 401(k) plans (in plan) | plan	2
401(k) savings plan employer contribution | $	$ 855	$ 724	$ 691