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Financings and Capitalization (Forward Stock Contracts) (Details) - $ / shares | Feb. 21, 2019 | Nov. 20, 2018 | Nov. 16, 2018
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Forward Contracts Maturing May 16, 2020 |  |  |
Debt and Equity Securities, FV-NI [Line Items] |  |  |
Number of Shares |  |  | 2,017,783
Initial forward price (in dollars per share) |  |  | $ 49.06
Forward Contracts Maturing May 20, 2020 |  |  |
Debt and Equity Securities, FV-NI [Line Items] |  |  |
Number of Shares |  | 777,899 |
Initial forward price (in dollars per share) |  | $ 50.91 |
Forward Contracts Maturing August 21, 2020 |  |  |
Debt and Equity Securities, FV-NI [Line Items] |  |  |
Number of Shares | 2,083,340 |  |
Initial forward price (in dollars per share) | $ 52.27 |  |

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