Stockholders' Equity Restricted Stock Unit Activity and Related Share-Based Compensation Expense (Details) shares in Thousands	6 Months Ended
	Jan. 31, 2017 $ / shares shares
Number of Shares
Nonvested at beginning of period (in shares) | shares	9,039
Granted, Number of shares (in shares) | shares	591
Vested, Number of Shares (in shares) | shares	(1,134)
Forfeited, Number of Shares (in shares) | shares	(830)
Nonvested at end of period (in shares) | shares	7,666
Weighted Average Grant Date Fair Value
Nonvested, Weighted Average Grant Date Fair Value, at beginning of period (in USD per shares) | $ / shares	$ 82.30
Granted, Weighted Average Grant Date Fair Value (in USD per shares) | $ / shares	111.92
Vested, Weighted Average Grant Date Fair Value (in USD per shares) | $ / shares	61.94
Forfeited, Weighted Average Grant Date Fair Value (in USD per shares) | $ / shares	70.36
Nonvested, Weighted Average Grant Date Fair Value, at end of period (in USD per shares) | $ / shares	$ 88.89