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Basis of Presentation and Preparation - Contingent Consideration, Concentration of Credit Risk, and Revenue Recognition (Details) | 12 Months Ended |
--- | --- | ---
Sep. 30, 2018 segment Institution | Oct. 01, 2018
Concentration of Credit Risk |  |
Financial institutions, in any such number of which investment exposure is limited | Institution | 1 |
Accounts receivable due from various agencies of the U.S. federal government (as a percent) | 26.00% |
Number of operating segments | segment | 2 |
Retained Earnings | Scenario, Forecast | Accounting Standards Update 2014-09 |  |
Concentration of Credit Risk |  |
Cumulative effect adjustment, percentage decrease in retained earnings (less than) |  | 2.00%
Minimum |  |
Contingent Consideration |  |
Period for contingent earn-out payments | 2 years |
Maximum |  |
Contingent Consideration |  |
Period for contingent earn-out payments | 3 years |
U.S. government |  |
Concentration of Credit Risk |  |
Revenue from customers (as a percent) | 49.00% |
U.S commercial |  |
Concentration of Credit Risk |  |
Revenue from customers (as a percent) | 26.00% |
International |  |
Concentration of Credit Risk |  |
Revenue from customers (as a percent) | 25.00% |

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