Income Taxes (Significant components of the Company's deferred tax assets and liabilities) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Deferred Tax Assets:
Property and casualty claim and claim adjustment expense reserves	$ 289	$ 352
Unearned premium reserves	178	162
Receivables	50	60
Employee benefits	187	384
Life settlement contracts	46	45
Deferred retroactive reinsurance benefit	66
Other assets	149	160
Gross deferred tax assets	965	1,163
Deferred Tax Liabilities:
Investment valuation differences	68	38
Deferred acquisition costs	232	238
Net unrealized gains	383	737
Other liabilities	62	57
Gross deferred tax liabilities	745	1,070
Net deferred tax asset (liability)	$ 220	$ 93