Reinsurance (Effects of Reinsurance on Balance Sheet) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Assets
Premiums and Other Receivables, Net	$ 20,443	$ 19,644
Deferred Policy Acquisition Costs and Present Value of Future Insurance Profits, Net	17,833	18,895	$ 18,419
Total assets	38,276	38,539
Liabilities
Future policy benefits	194,909	186,780
Policyholder account balances	192,627	183,693
Other policy-related balances	17,171	16,529
Other Liabilities	24,179	22,964
Total liabilities	428,886	409,966
Direct Reinsurance [Member]
Assets
Premiums and Other Receivables, Net	6,814	5,988
Deferred Policy Acquisition Costs and Present Value of Future Insurance Profits, Net	17,822	18,812
Total assets	24,636	24,800
Liabilities
Future policy benefits	191,403	183,367
Policyholder account balances	192,328	183,207
Other policy-related balances	15,806	15,519
Other Liabilities	16,165	14,848
Total liabilities	415,702	396,941
Assumed Reinsurance [Member]
Assets
Premiums and Other Receivables, Net	2,190	1,603
Deferred Policy Acquisition Costs and Present Value of Future Insurance Profits, Net	301	385
Total assets	2,491	1,988
Liabilities
Future policy benefits	3,506	3,413
Policyholder account balances	299	488
Other policy-related balances	1,351	986
Other Liabilities	2,402	2,131
Total liabilities	7,558	7,018
Ceded Reinsurance [Member]
Assets
Premiums and Other Receivables, Net	11,439	12,053
Deferred Policy Acquisition Costs and Present Value of Future Insurance Profits, Net	(290)	(302)
Total assets	11,149	11,751
Liabilities
Future policy benefits	0	0
Policyholder account balances	0	(2)
Other policy-related balances	14	24
Other Liabilities	5,612	5,985
Total liabilities	$ 5,626	$ 6,007