Statements Of Capital (USD $) In Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Balance			$ 1,783,478	$ 1,945,910
Proceeds from issuance of capital stock			45,895	57,219
Repurchase/redemption of capital stock			(2,545)
Comprehensive income (loss):
Net income (loss)	23,837	10,058	47,959	(19,532)
Other comprehensive income (loss):
Non-credit portion
Reclassification of non-credit portion included in net income
Accretion of non-credit portion
Amortization of prior service cost
Amortization of net loss
Total comprehensive income (loss)			48,452	(31,969)
Net reclassification of shares to mandatorily redeemable capital stock			(133,109)	(95,129)
Net transfer between Class A and Class B			0	0
Dividends on capital stock
Cash payment			(206)	(166)
Stock issued			0	0
Balance	1,741,965	1,875,865	1,741,965	1,875,865
Capital Stock Class A [Member]
Balance, shares			5,934	2,936
Balance			593,386	293,554
Proceeds from issuance of capital stock, shares			46	32
Proceeds from issuance of capital stock			4,657	3,229
Other comprehensive income (loss):
Non-credit portion
Reclassification of non-credit portion included in net income
Accretion of non-credit portion
Amortization of prior service cost
Amortization of net loss
Net reclassification of shares to mandatorily redeemable capital stock, shares			(1,144)	(10)
Net reclassification of shares to mandatorily redeemable capital stock			(114,435)	(1,025)
Net transfer between Class A and Class B			108,511	11,633
Net transfer between Class A and Class B, shares			1,085	116
Dividends on capital stock
Balance, shares	5,921	3,074	5,921	3,074
Balance	592,119	307,391	592,119	307,391
Capital Stock Class B [Member]
Balance, shares			8,610	13,091
Balance			861,010	1,309,142
Proceeds from issuance of capital stock, shares			412	540
Proceeds from issuance of capital stock			41,238	53,990
Repurchase/redemption of capital stock, shares			(25)
Repurchase/redemption of capital stock			(2,545)
Other comprehensive income (loss):
Non-credit portion
Reclassification of non-credit portion included in net income
Accretion of non-credit portion
Amortization of prior service cost
Amortization of net loss
Net reclassification of shares to mandatorily redeemable capital stock, shares			(187)	(941)
Net reclassification of shares to mandatorily redeemable capital stock			(18,674)	(94,104)
Net transfer between Class A and Class B			(108,511)	(11,633)
Net transfer between Class A and Class B, shares			(1,085)	(116)
Dividends on capital stock
Stock issued, shares			130	206
Stock issued			12,978	20,607
Balance, shares	7,855	12,780	7,855	12,780
Balance	785,496	1,278,002	785,496	1,278,002
Retained Earnings [Member]
Balance			351,754	355,075
Comprehensive income (loss):
Net income (loss)			47,959	(19,532)
Other comprehensive income (loss):
Non-credit portion
Reclassification of non-credit portion included in net income
Accretion of non-credit portion
Amortization of prior service cost
Amortization of net loss
Dividends on capital stock
Cash payment			(206)	(166)
Stock issued			(12,978)	(20,607)
Balance	386,529	314,770	386,529	314,770
Accumulated Other Comprehensive Income (Loss) [Member]
Balance			(22,672)	(11,861)
Other comprehensive income (loss):
Non-credit portion			(3,488)	(16,398)
Reclassification of non-credit portion included in net income			1,715	2,301
Accretion of non-credit portion			2,088	1,572
Amortization of prior service cost				(3)
Amortization of net loss			178	91
Dividends on capital stock
Balance	$ (22,179)	$ (24,298)	$ (22,179)	$ (24,298)