Investment In Unconsolidated Affiliate (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010
Investments in and Advances to Affiliates [Line Items]
Dividend from unconsolidated affiliate	$ 12	$ 40
StoneRiver Group, L.P. [Member]
Investments in and Advances to Affiliates [Line Items]
Cash dividend from affiliate	54	61
Percentage of interest owned in affiliate	49.00%
Dividend from unconsolidated affiliate	12	40
Obligations retired in other long-term liabilities		59
Retirement of loans receivable due from unconsolidated affiliate		59
Proceeds from loan repayments from unconsolidated affiliate		28
Investments in affiliate	$ 119	$ 156