Fair Value Measurement (Narrative) (Details) (USD $)	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Fair Value Measurement [Abstract]
Other Company Stock Owned Fair Value Discount Percentage	5.00%
Transfer of trading securities from Level 1 to Level 2 measurements	$ 767,000
Net gain (loss) representing the change in fair value in earnings	$ 14,000,000	$ 3,400,000	$ 247,000,000

For each line item in the statement of financial position, the amounts of gains and losses from fair value changes included in earnings.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

-Section 50

-Paragraph 30

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=6957238&loc=d3e14172-108612

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