Stock-Based Compensation - Restricted Stock (Details) - Restricted stock and restricted stock units	12 Months Ended
	Jan. 31, 2020 $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Balance as of the beginning of the period (in shares) | shares	7,703,705
Granted - restricted stock and restricted stock units (in shares) | shares	6,770,144
Vested and converted to shares (in shares) | shares	(2,962,280)
Canceled (in shares) | shares	(1,600,840)
Balance as of the end of period (in shares) | shares	9,910,729
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Balance as of the beginning of the period (in dollars per share) | $ / shares	$ 16.07
Granted - restricted stock and restricted stock units (in dollars per share) | $ / shares	18.71
Vested and converted to shares (in dollars per share) | $ / shares	16.04
Canceled (in dollars per share) | $ / shares	18.81
Balance as of the end of period (in dollars per share) | $ / shares	$ 17.44