Goodwill (details) - Other Intangible Assets (USD $) In Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010	Dec. 31, 2010
Other intangible assets by major asset class
Intangible assets subject to amortization, gross carrying amount	$ 1,126		$ 1,126		$ 1,126
Intangible assets subject to amortization, accumulated amortization	877		877		840
Intangible assets subject to amortization, net	249		249		286
Amortization expense for other intangible assets	17	21	37	45
Customer-related [Member]
Other intangible assets by major asset class
Intangible assets subject to amortization, gross carrying amount	935		935		935
Intangible assets subject to amortization, accumulated amortization	808		808		783
Intangible assets subject to amortization, net	127		127		152
Amortization expense for other intangible assets	11	15	25	32
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	69		69		57
Intangible assets subject to amortization, net	122		122		134
Amortization expense for other intangible assets	$ 6	$ 6	$ 12	$ 13