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Common Stock Common Stock (Details) - shares | 3 Months Ended | 9 Months Ended |
--- | --- | --- | ---
Sep. 30, 2019 | Sep. 30, 2019 | Dec. 31, 2018
Class of Stock [Line Items] |  |  |
Sales Agency Agreements Common Stock, Shares Authorized | 200,000,000 | 200,000,000 | 200,000,000
Document Period End Date |  | Sep. 30, 2019 |
Sales Agency Agreement [Member] |  |  |
Class of Stock [Line Items] |  |  |
Shares issued from sales agency agreements | 600,000 | 1,000,000.0 |
Sales Agency Agreements Common Stock, Shares Authorized | 4,600,000 | 4,600,000 |
Common Stock Shares Authorized Under Sales Agency Agreements Remaining Shares Authorized To Sell | 3,600,000 | 3,600,000 |

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