Leases - Summary of Supplemental Balance Sheet Information for Leases (Details) - USD ($) $ in Thousands	Jul. 31, 2019	Jan. 31, 2019	Jul. 31, 2018
ASSETS
Operating	$ 91,119	$ 0	$ 0
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	us-gaap:OperatingLeaseRightOfUseAsset
Finance	$ 341
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	us-gaap:OtherAssetsNoncurrent
Current liabilities:
Operating	$ 14,609	0	0
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	us-gaap:OperatingLeaseLiabilityCurrent
Finance	$ 114
Finance Lease, Liability, Current, Statement of Financial Position [Extensible List]	us-gaap:AccruedLiabilitiesCurrent
Noncurrent:
Operating	$ 82,972	$ 0	$ 0
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	us-gaap:OperatingLeaseLiabilityNoncurrent
Finance	$ 229
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	us-gaap:OtherLiabilitiesNoncurrent