Contingencies, Commitments and Guarantees (Insolvency Assessments) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Other Assets:
Premium tax offset for future discounted and undiscounted assessments	$ 43	$ 47
Premium tax offset currently available for paid assessments	43	46
Other Liabilities:
Insolvency assessments	62	67
Insurance-related Assessments
Other Assets:
Total assets held for insolvency assessments	$ 86	$ 93