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Equity Share Repurchases (Details) - USD ($) shares in Millions, $ in Millions | 1 Months Ended | 3 Months Ended |  |
--- | --- | --- | --- | ---
Apr. 24, 2019 | Mar. 31, 2019 | Mar. 31, 2018 | Sep. 30, 2018 | Sep. 30, 2016
Class of Stock [Line Items] |  |  |  |  |
Payments for repurchase of common stock |  | $ 655.8 | $ 250.0 |  |
2019 Share Repurchase Program |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |
Stock Repurchase Program, Authorized Amount |  | $ 5,000.0 |  |  |
2018 Share Repurchase Program |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |
Stock Repurchase Program, Authorized Amount |  |  |  | $ 3,500.0 |
Repurchase of common stock, at cost, shares |  | 2.4 |  |  |
Payments for repurchase of common stock |  | $ 655.8 |  |  |
2016 Share Repurchase Program |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |
Stock Repurchase Program, Authorized Amount |  |  |  |  | $ 5,000.0
Repurchase of common stock, at cost, shares |  |  | 0.9 |  |
Payments for repurchase of common stock |  |  | $ 250.0 |  |
Subsequent Event | 2018 Share Repurchase Program |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |
Stock Repurchase Program, Authorized Amount | $ 1,000.0 |  |  |  |
Repurchase of common stock, at cost, shares | 0.0 |  |  |  |
Payments for repurchase of common stock | $ 491.6 |  |  |  |

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