Income Taxes - Summary of Net Operating Loss Carryforwards and Tax Credit Carryforwards (Details) $ in Thousands	12 Months Ended
	Jan. 31, 2018 USD ($)
Federal
Income Tax Disclosure [Line Items]
Net operating losses	$ 348,210
Tax credits	$ 7,778
Net operating losses, beginning year	2028
Net operating losses, ending year	2038
Tax credits, beginning year	2030
Tax credits, ending year	2038
California
Income Tax Disclosure [Line Items]
Net operating losses	$ 50,706
Net operating losses, beginning year	2028
Net operating losses, ending year	2038
Other States
Income Tax Disclosure [Line Items]
Net operating losses	$ 103,064
Net operating losses	Various
State
Income Tax Disclosure [Line Items]
Tax credits	$ 7,431
Tax credits	Indefinite