Quarterly report pursuant to Section 13 or 15(d)

Trading Securities, at Fair Value (Details)

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Trading Securities, at Fair Value (Details) (USD $)
3 Months Ended
Mar. 31, 2012
Mar. 31, 2011
Dec. 31, 2011
Schedule of Trading Securities and Other Trading Assets [Line Items]      
Trading Securities, Cost $ 1,000,000,000    
Trading Securities 1,002,090,000   1,003,301,000
Trading Securities, Gross Unrealized Gain (Loss) 1,900,000   3,100,000
Proceeds from sales of trading securities 0 199,500,000  
Trading Securities, Amortized Cost Sold   200,000,000  
Trading Securities, Realized Gain (Loss)   (500,000)  
Trading Securities, Change in Unrealized Holding Gain (Loss) $ (1,200,000) $ 400,000