Investments (Net Investment Income on Leveraged and Direct Financing Leases) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Investments, All Other Investments [Abstract]
Leveraged Leases, Income Statement, Income from Leveraged Leases	$ 48	$ 47	$ 19
Leveraged Leases, Income Statement, Income Tax Expense on Leveraged Leases	(10)	(10)	(7)
Leveraged Leases, Income (Loss)	38	37	12
Capital Leases, Income Statement, Direct Financing Lease Revenue	109	95	89
Direct Financing Leases Income Statement Tax Expense on Direct Financing Leases	(23)	(20)	(31)
Direct Financing Leases Income Statement Net Income from Direct Financing Leases	$ 86	$ 75	$ 58