Employee Retirement Plans and Incentive Compensation Plans (Weighted-Average Assumptions in Determining Benefit Obligations) (Details)	Dec. 31, 2019	Dec. 31, 2018
Cash Balance Plan
Defined Benefit Plan Disclosure [Line Items]
Discount rate	2.75%	3.75%
Post-retirement Health Benefit Plan
Defined Benefit Plan Disclosure [Line Items]
Discount rate	3.00%	4.00%

Weighted average rate for present value of future retirement benefits cash flows, used to determine benefit obligation of defined benefit plan.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (k)(1)
-URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920

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