Goodwill (details) - Other Intangible Assets (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011
Other intangible assets by major asset class
Intangible assets subject to amortization, gross carrying amount	$ 646		$ 646		$ 1,126
Intangible assets subject to amortization, accumulated amortization	469		469		909
Intangible assets subject to amortization, net	177		177		217
Amortization expense for other intangible assets	12	16	40	53
Customer-related [Member]
Other intangible assets by major asset class
Intangible assets subject to amortization, gross carrying amount	455		455		935
Intangible assets subject to amortization, accumulated amortization	376		376		830
Intangible assets subject to amortization, net	79		79		105
Amortization expense for other intangible assets	8	11	26	36
Fair value adjustment on claims and claim adjustment expense reserves and reinsurance recoverables [Member]
Other intangible assets by major asset class
Intangible assets subject to amortization, gross carrying amount	191		191		191
Intangible assets subject to amortization, accumulated amortization	93		93		79
Intangible assets subject to amortization, net	98		98		112
Amortization expense for other intangible assets	$ 4	$ 5	$ 14	$ 17