Restricted Stock Units (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	3 Months Ended
	Jan. 31, 2019	Apr. 30, 2019	Apr. 30, 2018
Weighted-Average Grant Date Fair Value
Stock-based compensation expense		$ 62,157	$ 43,955
Restricted Stock Units
Number of Restricted Stock Units Outstanding
Unvested, Beginning balance (in shares)		21,917,550
Granted (in shares)		6,547,013
Vested (in shares)		(2,076,099)
Forfeited (in shares)		(448,975)
Unvested, Ending balance (in shares)	21,917,550	25,939,489
Weighted-Average Grant Date Fair Value
Beginning balance (in dollars per share)		$ 17.94
Granted (in dollars per share)		20.92
Vested (in dollars per share)		15.25
Forfeited (in dollars per share)		18.51
Ending balance (in dollars per share)	$ 17.94	$ 18.90
Aggregate Intrinsic Value	$ 392,515	$ 592,933
Share-based Compensation Capitalized Amount		37,300	26,400
Compensation not yet recognized		$ 447,100
Compensation cost (in years)		3 years 1 month 6 days
Restricted Stock
Number of Restricted Stock Units Outstanding
Unvested, Beginning balance (in shares)		2,267,569
Vested (in shares)		(622,662)
Unvested, Ending balance (in shares)	2,267,569	2,983,879
Weighted-Average Grant Date Fair Value
Beginning balance (in dollars per share)		$ 18.70
Vested (in dollars per share)		20.76
Ending balance (in dollars per share)	$ 18.70	$ 19.18
Aggregate Intrinsic Value	$ 40,612	$ 68,211
Compensation cost (in years)		2 years 7 months 6 days
Stock-based compensation expense		$ 7,500	$ 3,500
Previously Issued Performance Awards | Restricted Stock
Number of Restricted Stock Units Outstanding
Granted (in shares)		108,494