Equity Incentive Plans - Restricted Stock Activity (Details)	6 Months Ended
	Jul. 31, 2020 $ / shares shares
Restricted stock units
Number of Shares
Stock units outstanding, beginning balance (in shares) | shares	9,019,681
Stock units granted (in shares) | shares	3,141,965
Stock units vested (in shares) | shares	(2,762,734)
Stock units cancelled and expired (in units) | shares	(307,836)
Stock units outstanding, ending balance (in shares) | shares	9,091,076
Weighted Average Grant Date Fair Value
Weighted average grant date fair value, stock units outstanding, beginning balance (in usd per share) | $ / shares	$ 16.07
Weighted average grant date fair value, stock units granted (in usd per share) | $ / shares	22.84
Weighted average grant date fair value, stock units vested (in usd per share) | $ / shares	13.86
Weighted average grant date fair value, stock units cancelled or expired (in usd per share) | $ / shares	21.85
Weighted average grant date fair value, stock units outstanding, ending balance (in usd per share) | $ / shares	$ 18.88
Performance Based Restricted Stock Units
Number of Shares
Stock units outstanding, beginning balance (in shares) | shares	826,333
Stock units granted (in shares) | shares	349,945
Stock units vested (in shares) | shares	0
Stock units cancelled and expired (in units) | shares	(67,200)
Stock units outstanding, ending balance (in shares) | shares	1,109,078
Weighted Average Grant Date Fair Value
Weighted average grant date fair value, stock units outstanding, beginning balance (in usd per share) | $ / shares	$ 13.95
Weighted average grant date fair value, stock units granted (in usd per share) | $ / shares	22.30
Weighted average grant date fair value, stock units vested (in usd per share) | $ / shares	0
Weighted average grant date fair value, stock units cancelled or expired (in usd per share) | $ / shares	13.41
Weighted average grant date fair value, stock units outstanding, ending balance (in usd per share) | $ / shares	$ 16.62