Goodwill (details) - Other Intangible Assets (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 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	457		457		909
Intangible assets subject to amortization, net	189		189		217
Amortization expense for other intangible assets	12	17	28	37
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	368		368		830
Intangible assets subject to amortization, net	87		87		105
Amortization expense for other intangible assets	7	11	18	25
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	89		89		79
Intangible assets subject to amortization, net	102		102		112
Amortization expense for other intangible assets	$ 5	$ 6	$ 10	$ 12