Contract Balances and Contract Costs - Remaining Performance Obligation Time Period (Details)	Jul. 31, 2020
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-08-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligation period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-08-01 | Performance obligation - active
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligation period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-08-01 | Performance obligation - backlog
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligation period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-07-31
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligation period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-07-31 | Performance obligation - active
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligation period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-07-31 | Performance obligation - backlog
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligation period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-07-30
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligation period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-07-30 | Performance obligation - active
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligation period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-07-30 | Performance obligation - backlog
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligation period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-07-29
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligation period
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-07-29 | Performance obligation - active
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligation period
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-07-29 | Performance obligation - backlog
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligation period