Income Taxes (Details 2) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Deferred tax liabilities:
Net deferred income tax asset	$ 37	$ 19
Net deferred tax liability	365	147
Net deferred income tax asset (liability)	(328)	(128)
Indemnity
Deferred tax assets:
Net allowance for service fees and premium cancellations	3	3
Other employee benefits	9	9
Pension and other postretirement benefits	65	45
Other	3	1
Total deferred tax assets	80	58
Deferred tax liabilities:
Unrealized gains on investments	6	6
Limited partnerships	13	10
Depreciation	15	13
Prepaid expenses	5	7
Capitalized internally developed software	3	1
Other	1	2
Total deferred tax liabilities	43	39
Net deferred income tax asset	37	19
Net deferred tax liability
Exchange
Deferred tax assets:
Loss reserve discount	78	81
Liability for future life and annuity policy benefits	7	12
Unearned premiums	179	165
Write-downs of impaired securities	19	29
Other	22	27
Total deferred tax assets	305	314
Deferred tax liabilities:
Deferred policy acquisition costs	165	159
Unrealized gains on investments	443	272
Limited partnerships	43	12
Other	19	18
Total deferred tax liabilities	670	461
Net deferred tax liability	$ 365	$ 147