Short-Term and Long-Term Debt (Schedule Of Debt) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2016	Apr. 30, 2016
Debt Instrument [Line Items]
Current maturities of long-term debt		$ 450
Total short-term debt		450
Total long-term debt		$ 4,894		$ 5,345
Fixed rate, swap		5.00%
Long-term Debt [Member]
Debt Instrument [Line Items]
Senior Long Term Notes		$ 3,460		3,910
Capital Securities		1,213		1,213
Unamortized premiums (discounts)		(8)		(9)
Unamortized debt issuance costs		(25)		(27)
Fair value hedge - interest rate swap agreements		254		258
Total unamortized premiums (discounts), unamortized debt issuance costs and fair value hedges on interest rate swap agreements		221		222
Total long-term debt		4,894		5,345
Parent Company [Member]
Debt Instrument [Line Items]
Total short-term debt		450
Total long-term debt		$ 4,894		5,343
7.00% notes, due 2018 [Member] | Long-term Debt [Member]
Debt Instrument [Line Items]
Senior Long Term Notes				200
Interest rate		7.00%
LIBOR plus 110 bps loan, due 2018 [Member] | Long-term Debt [Member]
Debt Instrument [Line Items]
Senior Long Term Notes				250
Variable rate		1.10%
8.75% notes, due 2019 [Member] | Long-term Debt [Member]
Debt Instrument [Line Items]
Senior Long Term Notes	[1]	$ 287		287
Interest rate	[1]	8.75%
6.25% notes, due 2020 [Member] | Long-term Debt [Member]
Debt Instrument [Line Items]
Senior Long Term Notes	[1]	$ 300		300
Interest rate	[1]	6.25%
4.85% notes, due 2021 [Member] | Long-term Debt [Member]
Debt Instrument [Line Items]
Senior Long Term Notes	[1]	$ 300		300
Interest rate	[1]	4.85%
4.20% notes, due 2022 [Member] | Long-term Debt [Member]
Debt Instrument [Line Items]
Senior Long Term Notes	[1]	$ 300		300
Interest rate	[1]	4.20%
4.00% notes, due 2023 [Member] | Long-term Debt [Member]
Debt Instrument [Line Items]
Senior Long Term Notes	[1]	$ 350		350
Interest rate	[1]	4.00%
3.35% notes, due 2025 [Member] | Long-term Debt [Member]
Debt Instrument [Line Items]
Senior Long Term Notes	[1]	$ 300		300
Interest rate	[1]	3.35%
3.63% notes, due 2026 [Member] | Long-term Debt [Member]
Debt Instrument [Line Items]
Senior Long Term Notes	[1]	$ 400		400
Interest rate	[1]	3.63%
6.15% notes, due 2036 [Member] | Long-term Debt [Member]
Debt Instrument [Line Items]
Senior Long Term Notes	[1]	$ 348		348
Interest rate	[1]	6.15%
6.30% notes, due 2037 [Member] | Long-term Debt [Member]
Debt Instrument [Line Items]
Senior Long Term Notes	[1],[2]	$ 375		375
Interest rate	[1],[2]	6.30%
7.00% notes, due 2040 [Member] | Long-term Debt [Member]
Debt Instrument [Line Items]
Senior Long Term Notes	[1],[2]	$ 500		500
Interest rate	[1],[2]	7.00%
LIBOR +236 bps, due 2066 [Member] | Long-term Debt [Member]
Debt Instrument [Line Items]
Capital Securities	[3]	$ 722		722
Interest rate					7.00%
Variable rate	[3]	2.36%
LIBOR +204 bps, due 2067 [Member] | Long-term Debt [Member]
Debt Instrument [Line Items]
Capital Securities	[3]	$ 491		$ 491
Interest rate			6.05%
Variable rate	[3]	2.04%

[1] We have the option to repurchase the outstanding notes by paying the greater of 100% of the principal amount of the notes to be redeemed or the make-whole amount (as defined in each note agreement), plus in each case any accrued and unpaid interest as of the date of redemption.Categorized as operating debt for leverage ratio calculations as the proceeds were used as a long-term structured solution to reduce the strain on increasing statutory reserves associated with secondary guarantee UL and term policies.In May 2016, the capital securities due 2066 changed from a 7.00% fixed rate to a floating rate of LIBOR + 236 bps. In April 2017, the capital securities due 2067 changed from a 6.05% fixed rate to a floating rate of LIBOR + 204 bps. To hedge the variability in rates, we purchased forward starting swaps to lock in a fixed rate of approximately 5% over the remaining terms of the capital securities, respectively.

[2] Categorized as operating debt for leverage ratio calculations as the proceeds were used as a long-term structured solution to reduce the strain on increasing statutory reserves associated with secondary guarantee UL and term policies.

[3] In May 2016, the capital securities due 2066 changed from a 7.00% fixed rate to a floating rate of LIBOR + 236 bps. In April 2017, the capital securities due 2067 changed from a 6.05% fixed rate to a floating rate of LIBOR + 204 bps. To hedge the variability in rates, we purchased forward starting swaps to lock in a fixed rate of approximately 5% over the remaining terms of the capital securities, respectively.