Segment Information (Reconciliation of Revenue from Segments to Consolidated) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	$ 4,143	$ 3,643	$ 3,606	$ 3,204	$ 3,785	$ 3,628	$ 3,467	$ 3,420	$ 14,596	$ 14,300	$ 12,876
Americas [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues									7,780	7,779	7,203
Canada Segment Reporting Information [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues									1,352	1,385	1,273
EMEA [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues									2,104	1,970	1,845
Asia Pacific [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues									3,115	2,909	2,471
Corporate And Other Segment Reporting Information [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues									245	257	84
Life Insurance Product Line [Member] | Americas [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues									6,560	6,500	6,296
Life Insurance Product Line [Member] | Canada Segment Reporting Information [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues									1,260	1,286	1,224
Life Insurance Product Line [Member] | EMEA [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues									1,633	1,520	1,495
Life Insurance Product Line [Member] | Asia Pacific [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues									2,806	2,681	2,417
Insurance, Other [Member] | Americas [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues									1,220	1,279	907
Insurance, Other [Member] | Canada Segment Reporting Information [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues									92	99	49
Insurance, Other [Member] | EMEA [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues									471	450	350
Insurance, Other [Member] | Asia Pacific [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues									$ 309	$ 228	$ 54