Goodwill (details) - Other Intangible Assets (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Dec. 31, 2011
Other intangible assets by major asset class
Intangible assets subject to amortization, gross carrying amount	$ 646		$ 1,126
Intangible assets subject to amortization, accumulated amortization	445		909
Intangible assets subject to amortization, net	201		217
Amortization expense for other intangible assets	16	20
Customer-related [Member]
Other intangible assets by major asset class
Intangible assets subject to amortization, gross carrying amount	455		935
Intangible assets subject to amortization, accumulated amortization	361		830
Intangible assets subject to amortization, net	94		105
Amortization expense for other intangible assets	11	14
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
Intangible assets subject to amortization, accumulated amortization	84		79
Intangible assets subject to amortization, net	107		112
Amortization expense for other intangible assets	$ 5	$ 6