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Significant Transactions - PassportCard/DavidShield (Details) - USD ($) $ in Millions | May 07, 2020 | Jan. 24, 2018 | Jun. 30, 2021 | Dec. 31, 2020 | May 06, 2020
--- | --- | --- | --- | --- | ---
DavidShield |  |  |  |  |
Other Significant Noncash Transactions [Line Items] |  |  |  |  |
Ownership interest (as a percent) |  | 50.00% |  |  |
PassportCard |  |  |  |  |
Other Significant Noncash Transactions [Line Items] |  |  |  |  |
Ownership interest (as a percent) |  | 50.00% |  |  |
PassportCard/DavidShield |  |  |  |  |
Other Significant Noncash Transactions [Line Items] |  |  |  |  |
Ownership interest (as a percent) | 53.80% |  | 53.80% | 53.80% | 50.00%
Payments to acquire businesses, gross |  | $ 41.8 |  |  |
Payments to acquire business, net |  | $ 28.3 |  |  |
Stock issued during period, value, acquisitions | $ 15.0 |  |  |  |
Maximum loss exposure |  |  | $ 104.0 |  |

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