Debt (Aggregate Maturity Of Debt Obligations) (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011
Corporate Obligations [Member]
Debt Instrument [Line Items]
2013
2014
2015
2016
2017
Thereafter	723
Long-term Debt, Total	723
14% Surplus Notes Due 2033 [Member]
Debt Instrument [Line Items]
Callable, price	100.00		100.00
2013		[1]
2014		[1]
2015		[1]
2016		[1]
2017		[1]
Thereafter	940	[1]
Long-term Debt, Total	940	[1]
Debt [Member]
Debt Instrument [Line Items]
2013
2014
2015
2016
2017
Thereafter	1,663
Long-term Debt, Total	$ 1,663
6.400% Senior Notes Due 2022 [Member]
Debt Instrument [Line Items]
Callable, price	100.00		100.00
5.700% Senior Notes Due 2034 [Member]
Debt Instrument [Line Items]
Callable, price	100.00		100.00

[1] Callable on or after January 15, 2018 and every fifth anniversary thereafter at 100.00.