Summary Of Significant Accounting Policies (Narrative) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended			12 Months Ended	3 Months Ended	12 Months Ended
	Mar. 31, 2012 Y	Mar. 31, 2011	Dec. 31, 2011	Dec. 31, 2011 Deferred Policy Acquisition Costs [Member]	Dec. 31, 2010 Retained Earnings [Member]	Dec. 31, 2011 Retained Earnings [Member]	Dec. 31, 2010 Retained Earnings [Member]
Summary Of Significant Accounting Policies [Line Items]
Effect Of Adjustment Of Adoption Of New Accounting Guidance					$ 139		$ 139
Deferred policy acquisition costs	1,649		1,548
Cumulative effect of change in accounting principle				213		181
New accounting pronouncement effect of change on net income		$ 10
Deferred marketing costs recoverability and amortized years	10