Employee Benefit Plans - Net Periodic Benefit Costs Weighted Average Assumptions (Details)	12 Months Ended
Jan. 31, 2020	Jan. 31, 2019	Jan. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Expected return on plan assets (percentage)	7.00%	7.00%	7.00%
Qualified
Defined Benefit Plan Disclosure [Line Items]
Discount rate (percentage)	4.25%	4.00%	4.25%
Rate of Increase in compensation (percentage)	3.00%	3.00%	3.00%
Excess/SRIP
Defined Benefit Plan Disclosure [Line Items]
Discount rate (percentage)	4.25%	3.75%	4.25%
Rate of Increase in compensation (percentage)	6.50%	6.50%	6.50%
Other
Defined Benefit Plan Disclosure [Line Items]
Discount rate (percentage)	1.32%	1.54%	1.49%
Rate of Increase in compensation (percentage)	2.66%	1.41%	1.38%
Excess Plan
Defined Benefit Plan Disclosure [Line Items]
Rate of Increase in compensation (percentage)	4.25%	4.25%	4.25%
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Discount rate (percentage)	4.50%	4.00%	4.25%

Weighted average rate for present value of future retirement benefits cash flows, used to determine net periodic benefit cost 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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- Definition

Weighted average rate of return on plan assets, reflecting average rate of earnings expected on existing plan assets and expected contributions, used to determine net periodic benefit cost of defined benefit plan.

+ References

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)(3)
-URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920

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- Definition

Weighted average rate of compensation increase used to determine net periodic benefit cost of defined benefit plan. Plan includes, but is not limited to, pay-related defined benefit plan.

+ References

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)(2)
-URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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