Dispositions (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2012	Mar. 31, 2011
Disposal
Gain (loss) on disposal, before federal income taxes	$ (1)	$ 0

Pretax gain (loss), not previously recognized and resulting from the sale of a business component, which is recognized at the date of sale. A gain (loss) reflects the amount by which the consideration received exceeds (is exceeded by) the net carrying amount (reflecting previous provisions for loss on disposal, if any) of the disposal group.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 144

-Paragraph 43

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 144

-Paragraph 47

-Subparagraph b

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration