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Computation of Earnings Per Common Share - Narratives (Details) - USD ($) $ / shares in Units, $ in Thousands | 3 Months Ended | 6 Months Ended | 12 Months Ended |
--- | --- | --- | --- | ---
Jul. 28, 2018 | Apr. 28, 2018 | Jan. 25, 2018 | Jan. 27, 2018 | Jan. 25, 2020 | Jan. 26, 2019 | Jul. 29, 2017 | Sep. 15, 2015
Shares used in computing earnings per common share: |  |  |  |  |  |  |  |
Adoption of accounting principled effect on diluted shares |  |  |  | 177,575 |  |  |  |
Proceeds from borrowings on senior credit agreement, including term loans |  |  |  | $ 0 | $ 475,000 | $ 423,188 | $ 707,000 |
Convertible Note Hedge |  |  |  |  |  |  |  |
Shares used in computing earnings per common share: |  |  |  |  |  |  |  |
Debt instrument, convertible, conversion price (per share) |  |  |  |  | $ 96.89 | $ 96.89 |  | $ 96.89
Proceeds from borrowings on senior credit agreement, including term loans |  |  |  |  | $ 25,000 |  |  |
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (shares) |  |  |  |  |  |  |  | 4,748,000
0.75% Convertible Senior Notes Due 2021 |  |  |  |  |  |  |  |
Shares used in computing earnings per common share: |  |  |  |  |  |  |  |
Debt, interest rate (in percent) |  |  |  |  | 0.75% | 0.75% |  |
Debt instrument, convertible, conversion price (per share) |  |  |  |  |  |  |  | $ 96.89
Class of warrant or right, exercise price of warrants or rights (per warrant) |  |  |  |  | $ 130.43 |  |  |
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (shares) |  |  |  |  | 4,748,000 | 5,006,000 |  |
Warrant Transaction |  |  |  |  |  |  |  |
Shares used in computing earnings per common share: |  |  |  |  |  |  |  |
Class of warrant or right, exercise price of warrants or rights (per warrant) |  |  |  |  |  |  |  | $ 130.43
Proceeds from borrowings on senior credit agreement, including term loans |  |  |  |  | $ 25,000 |  |  |
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (shares) |  |  |  |  |  | 5,006,000.000 |  | 4,748,000
Weighted Average | 0.75% Convertible Senior Notes Due 2021 |  |  |  |  |  |  |  |
Shares used in computing earnings per common share: |  |  |  |  |  |  |  |
Average Stock Price (usd per share) | $ 99.27 | $ 110.46 | $ 106.11 |  |  |  |  |

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