Advances (Advance Redemption Terms) (Details) - USD ($) $ in Thousands		Jun. 30, 2017	Dec. 31, 2016
Advances [Abstract]
Due in 1 year or less		$ 36,268,570	$ 23,129,060
Due after 1 year through 2 years		17,263,673	21,503,138
Due after 2 years through 3 years		10,306,830	14,292,353
Due after 3 years through 4 years		1,887,708	5,322,050
Due after 4 years through 5 years		727,943	963,105
Thereafter		4,657,756	4,697,315
Federal Home Loan Bank, Advances, Par Value, Total		71,112,480	69,907,021
Commitment Fees on Advances		(522)	(534)
Discount on Affordable Housing Program Advances		(6,613)	(7,435)
Federal Home Loan Bank Advances, Premium		1,926	2,061
Federal Home Loan Bank Advances, Discount		(4,947)	(5,994)
Hedging adjustments		(14,316)	(13,138)
Federal Home Loan Bank, Advances, Valuation Adjustments under Fair Value Option	[1]	63	93
Advances		$ 71,088,071	$ 69,882,074
Federal Home Loan Bank Advances, Weighted Average Interest Rate of Amounts Maturing Within One Year of Balance Sheet Date		1.27%	0.85%
Federal Home Loan Bank Advances, Weighted Average Interest Rate of Amounts Maturing From One To Two Years of Balance Sheet Date		1.44%	1.06%
Federal Home Loan Bank Advances, Weighted Average Interest Rate of Amounts Maturing From Two To Three Years of Balance Sheet Date		1.49%	1.12%
Federal Home Loan Bank Advances, Weighted Average Interest Rate of Amounts Maturing From Three To Four Years of Balance Sheet Date		1.85%	1.26%
Federal Home Loan Bank Advances, Weighted Average Interest Rate of Amounts Maturing From Four To Five Years of Balance Sheet Date		2.11%	1.78%
Federal Home Loan Bank Advances, Weighted Average Interest Rate of Amounts Maturing After Five Years of Balance Sheet Date		1.95%	1.75%
Federal Home Loan Bank Advances, Weighted Average Interest Rate As Of Balance Sheet Date		1.41%	1.07%

[1] At June 30, 2017 and December 31, 2016, none of the Advances were 90 days or more past due or had been placed on non-accrual status.