General (Narrative) (Detail) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2011	Sep. 30, 2011	Dec. 31, 2011 Deferred Policy Acquisition Costs [Member]	Dec. 31, 2011 Retained Earnings [Member]	Dec. 31, 2010 Retained Earnings [Member]
General [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets					$ 139
Cumulative effect of change in accounting principle	$ 8	$ 30	$ 213	$ 181
New accounting pronouncement effect of change on earnings per share	$ 0.02	$ 0.09