Stockholders' Equity (Share Repurchases) (Details) - USD ($) |
3 Months Ended | 12 Months Ended | |||
---|---|---|---|---|---|
Apr. 30, 2019 |
Jan. 31, 2019 |
Oct. 31, 2018 |
Mar. 01, 2017 |
Feb. 28, 2017 |
|
Equity [Abstract] | |||||
Share Repurchase Program, maximum amount authorized | $ 1,000,000,000.0 | $ 500,000,000.0 | |||
Average purchase price (in usd per share) | $ 248.70 | ||||
Number of common stock repurchased, shares | 0 | 24,500 | 0 | ||
Treasury Stock, Value, Acquired, Cost Method | $ 6,100,000 | ||||
Share Repurchase Program, remaining authorized amount | $ 557,400,000 |