Contract Balances and Contract Costs - Remaining Performance Obligation Total (Details) $ in Thousands	Jul. 31, 2020 USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 302,403
Performance obligation - active
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	285,117
Performance obligation - backlog
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 17,286