Derivatives and Hedging Activities (Offsetting Liabilities) (Details) - USD ($) $ in Thousands		Sep. 30, 2020	Dec. 31, 2019
Offsetting Liabilities [Line Items]
Derivative Liability, Fair Value, Gross Liability		$ 5,226	$ 8,790
Derivative Liability, Fair Value, Gross Asset and Right to Reclaim Cash, Offset	[1],[2]	(3,578)	(5,845)
Derivative Laibility, Net Fair Value Amount, After Offsetting Adjustment		1,648	2,945
Derivative Liability, Not Subject to Master Netting Arrangement	[3]	103	79
Derivative liabilities		1,751	3,024
Derivative Liability, Fair Value, Amount Offset Against Collateral		1,751	3,024
Over the Counter [Member]
Offsetting Liabilities [Line Items]
Derivative Liability, Fair Value, Gross Liability		4,778	7,135
Derivative Liability, Fair Value, Gross Asset and Right to Reclaim Cash, Offset		(3,130)	(4,190)
Derivative Laibility, Net Fair Value Amount, After Offsetting Adjustment		1,648	2,945
Derivative Liability, Not Subject to Master Netting Arrangement		103	79
Derivative liabilities		1,751	3,024
Derivative Liability, Fair Value, Amount Offset Against Collateral		1,751	3,024
Exchange Cleared [Member]
Offsetting Liabilities [Line Items]
Derivative Liability, Fair Value, Gross Liability		448	1,655
Derivative Liability, Fair Value, Gross Asset and Right to Reclaim Cash, Offset		(448)	(1,655)
Derivative Laibility, Net Fair Value Amount, After Offsetting Adjustment		0	0
Derivative Liability, Not Subject to Master Netting Arrangement		0	0
Derivative liabilities		0	0
Derivative Liability, Fair Value, Amount Offset Against Collateral		$ 0	$ 0

[1] Amounts represent the application of the netting requirements that allow the Bank to settle positive and negative positions, cash collateral and related accrued interest held or placed with the same clearing agent and/or counterparties. Cash collateral posted and related accrued interest was $160.0 million and $138.1 million at September 30, 2020 and December 31, 2019, respectively. Cash collateral received was $2.9 million for September 30, 2020 and $8.2 million for December 31, 2019.

[2] Amounts represent the application of the netting requirements that allow the Bank to settle positive and negative positions and also cash collateral held and related interest accrued or placed by the Bank with the same clearing agent and/or counterparties.

[3] Represents derivatives that are not subject to an enforceable netting agreement (e.g., mortgage delivery commitments).