|
Stock Option Plan and Employee Stock Purchase Plan (Details) (USD $)
|
3 Months Ended |
9 Months Ended |
|
Apr. 30, 2011
|
Jan. 31, 2011
|
Oct. 31, 2010
|
Apr. 30, 2010
|
Apr. 30, 2011
|
Apr. 30, 2010
|
| Stock Option Plan and Employee Stock Purchase Plan |
 |
 |
 |
 |
 |
 |
| Aggregate maximum number of shares of common stock which may be issued under stock option plan |
8,962,500 |
 |
 |
 |
8,962,500 |
 |
| Maximum term for grants of incentive and non-qualified stock-based awards, excluding incentive stock-based awards granted to stockholders who own more than 10% of the voting power |
10 |
 |
 |
 |
10 |
 |
| Maximum term for incentive stock-based awards granted to stockholders who own more than 10% of the voting power |
5 |
 |
 |
 |
5 |
 |
| Percentage of a stockholder's voting power that limits the contractual term of an incentive stock-based award |
10.00% |
 |
 |
 |
10.00% |
 |
| Aggregate net number of stock-based awards granted under stock option plan |
6,529,470 |
 |
 |
 |
6,529,470 |
 |
| Aggregate Number Of Canceled Stock Based Awards Under Stock Option Plan |
1,253,730 |
 |
 |
 |
1,253,730 |
 |
| Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Lower Range Limit |
 |
 |
 |
 |
$ 3.13 |
 |
| Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Upper Range Limit |
 |
 |
 |
 |
$ 51.65 |
 |
| Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number, Ending Balance |
3,010,495 |
3,181,008 |
3,274,208 |
 |
3,010,495 |
 |
| Number of stock-based awards, including stock appreciation rights, exercised as of balance sheet date |
3,518,975 |
 |
 |
 |
3,518,975 |
 |
| Number of stock appreciation rights exercised as of balance sheet date |
750 |
 |
 |
 |
750 |
 |
| Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number, Beginning Balance |
3,181,008 |
3,274,208 |
3,520,667 |
 |
3,520,667 |
 |
| Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period |
30,000 |
|
2,000 |
 |
 |
 |
| Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures and Expirations in Period |
(184,663) |
(64,050) |
(210,664) |
 |
 |
 |
| Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period |
(15,850) |
(29,150) |
(37,795) |
 |
(82,795) |
(91,697) |
| Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number, Ending Balance |
3,010,495 |
3,181,008 |
3,274,208 |
 |
3,010,495 |
 |
| Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number |
1,824,592 |
 |
 |
 |
1,824,592 |
 |
| Share-based Compensation Arrangement by Share-based Payment Award, Options, Expected to Vest, Outstanding, Number |
1,059,097 |
 |
 |
 |
1,059,097 |
 |
| Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price, Beginning of Period |
$ 32.84 |
$ 32.78 |
$ 32.75 |
 |
$ 32.75 |
 |
| Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price |
$ 27.87 |
|
$ 27.35 |
 |
$ 27.87 |
 |
| Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures and Expirations in Period, Weighted Average Exercise Price |
$ 35.49 |
$ 38.16 |
$ 35.28 |
 |
 |
 |
| Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Weighted Average Exercise Price |
$ 18.54 |
$ 13.69 |
$ 16.21 |
 |
$ 18.54 |
 |
| Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price, End of Period |
$ 32.71 |
$ 32.84 |
$ 32.78 |
 |
$ 32.71 |
 |
| Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price |
$ 32.84 |
 |
 |
 |
$ 32.84 |
 |
| Share-based Compensation Arrangement by Share-based Payment Award, Options, Expected to Vest, Weighted Average Exercise Price |
$ 32.35 |
 |
 |
 |
$ 32.35 |
 |
| Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term |
3.52 |
 |
 |
 |
3.52 |
 |
| Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term |
 |
 |
 |
 |
2.04 |
 |
| Share-based Compensation Arrangement by Share-based Payment Award, Options, Expected to Vest, Weighted Average Remaining Contractual Term |
5.81 |
 |
 |
 |
5.81 |
 |
| Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value |
$ 5,197,000 |
 |
 |
 |
$ 5,197,000 |
 |
| Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value |
5,182,000 |
 |
 |
 |
5,182,000 |
 |
| Share-based Compensation Arrangement by Share-based Payment Award, Options, Expected to Vest, Intrinsic Value |
14,000 |
 |
 |
 |
14,000 |
 |
| Number of stock appreciation rights outstanding as of the balance sheet date |
38,500 |
 |
 |
 |
38,500 |
 |
| Total intrinsic value of stock-based awards exercised |
$ 148,000 |
 |
 |
$ 345,000 |
$ 1,135,000 |
$ 1,578,000 |
| Total number of common shares reserved for issuance under employee stock purchase plan |
675,000 |
 |
 |
 |
675,000 |
 |
| Percentage of fair market value at which eligible employees can acquire common stock under employee stock purchase plan |
85.00% |
 |
 |
 |
85.00% |
 |
| Total number of shares of common stock issued to employees under employee stock purchase plan and through the end of the reporting period |
416,718 |
 |
 |
 |
416,718 |
 |