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Acquisitions - Narrative (Details) - USD ($) $ in Millions | Dec. 10, 2018 | Oct. 30, 2018
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Benefit Consultants Group Inc. |  |
Business Acquisition [Line Items] |  |
Business acquisitions |  | $ 25
NTA Life Enterprises |  |
Business Acquisition [Line Items] |  |
Business acquisitions | $ 405 |

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