Accounting Policies (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended			3 Months Ended				12 Months Ended	3 Months Ended				12 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Dec. 31, 2011	Dec. 31, 2011 As previously reported [Member]	Sep. 30, 2011 As previously reported [Member]	Jun. 30, 2011 As previously reported [Member]	Mar. 31, 2011 As previously reported [Member]	Dec. 31, 2011 As previously reported [Member]	Dec. 31, 2011 As adjusted [Member]	Sep. 30, 2011 As adjusted [Member]	Jun. 30, 2011 As adjusted [Member]	Mar. 31, 2011 As adjusted [Member]	Dec. 31, 2011 As adjusted [Member]
Accounting Standards Adopted in 2012
Deferred policy acquisition costs	$ 916		$ 901	$ 1,105				$ 1,105	$ 901				$ 901
Net deferred tax liability (included in other liabilities)				203				203	133				133
Shareholders' equity	4,580		4,411	4,545				4,545	4,411				4,411
Net earnings attributable to shareholders	$ 113	$ 88		$ 109	$ 96	$ 55	$ 83	$ 343	$ 109	$ 97	$ 48	$ 88	$ 342
Diluted earnings per Common Share	$ 1.14	$ 0.83		$ 1.10	$ 0.94	$ 0.52	$ 0.79	$ 3.33	$ 1.09	$ 0.95	$ 0.46	$ 0.83	$ 3.32