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Shareholders' Equity - Prospectus Supplement (Details) - USD ($) | 3 Months Ended | 12 Months Ended |  |
--- | --- | --- | --- | ---
Mar. 31, 2016 | Dec. 31, 2015 | Nov. 10, 2014 | May. 08, 2013
Prospectus Supplement July 18, 2014 |  |  |  |
Class of Stock [Line Items] |  |  |  |
Maximum common stock value authorized under prospectus supplement |  |  |  | $ 100,000,000
Common Stock sold under prospectus supplement, in shares | 0 | 0 |  |
Prospectus Supplement November 10, 2014 |  |  |  |
Class of Stock [Line Items] |  |  |  |
Maximum common stock value authorized under prospectus supplement |  |  | $ 150,000,000 |
Common Stock sold under prospectus supplement, in shares | 0 | 0 |  |

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