Contract Balances and Contract Costs - Narrative (Details)	6 Months Ended
	Jul. 31, 2020 performance_obligation
Disaggregation of Revenue [Line Items]
Deferred revenue billed in advance, percent	58.00%
Deferred revenue billed monthly or quarterly, percent	42.00%
Number of elements performance obligation is comprised of	2
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-08-01
Disaggregation of Revenue [Line Items]
Performance obligation period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-08-01 | Managed Security Solutions revenue
Disaggregation of Revenue [Line Items]
Performance obligation period	2 years
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-08-01 | Security and Risk Consulting revenue
Disaggregation of Revenue [Line Items]
Performance obligation period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-07-31
Disaggregation of Revenue [Line Items]
Performance obligation period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-07-30
Disaggregation of Revenue [Line Items]
Performance obligation period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-07-29
Disaggregation of Revenue [Line Items]
Performance obligation period