Statement of Changes in Capital (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Total capital			$ 3,662,838	$ 4,160,882
Proceeds from sale of capital stock			321,423	55,450
Repurchase/redemption of capital stock			(436,079)	(538,824)
Net shares reclassified to mandatorily redeemable capital stock			(183,483)	(19,821)
Comprehensive income	140,002	6,904	268,781	113,413
Cash Dividends			(2,403)
Total capital	3,631,077	3,771,100	3,631,077	3,771,100
Common Stock [Member]
Total capital			3,389,863	3,986,932
Balance, Shares			33,899	39,869
Proceeds from sale of capital stock			321,423	55,450
Proceeds from sale of capital stock, shares			3,214	554
Repurchase/redemption of capital stock			(436,079)	(538,824)
Repurchase/Redemption of capital stock, Shares			(4,361)	(5,388)
Net shares reclassified to mandatorily redeemable capital stock, shares			(1,835)	(198)
Net shares reclassified to mandatorily redeemable capital stock			(183,483)	(19,821)
Total capital	3,091,724	3,483,737	3,091,724	3,483,737
Balance, Shares	30,917	34,837	30,917	34,837
Retained Earnings, Unappropriated [Member]
Total capital			430,774	397,291
Comprehensive income			62,392	24,727
Cash Dividends			(2,403)
Total capital	490,763	422,018	490,763	422,018
Retained Earnings, Appropriated [Member]
Total capital			4,566	0
Comprehensive income			15,598	2,377
Total capital	20,164	2,377	20,164	2,377
Retained Earnings [Member]
Total capital			435,340	397,291
Comprehensive income			77,990	27,104
Cash Dividends			(2,403)
Total capital	510,927	424,395	510,927	424,395
Accumulated Other Comprehensive Income (Loss) [Member]
Total capital			(162,365)	(223,341)
Comprehensive income			190,791	86,309
Total capital	$ 28,426	$ (137,032)	$ 28,426	$ (137,032)