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Revenue from Contracts with Customers (Details) - USD ($) | 3 Months Ended | 9 Months Ended | 12 Months Ended
--- | --- | --- | ---
Sep. 30, 2021 | Sep. 30, 2020 | Sep. 30, 2021 | Sep. 30, 2020 | Dec. 31, 2020
Business Acquisition [Line Items] |  |  |  |  |
Performance obligation satisfied in previous period | $ 0 | $ 4,400,000 | $ 0 | $ 6,100,000 |
Change in estimate of transaction price | 0 | 0 | 0 | 0 |
Change in total estimated cost | 0 | 0 | 0 | 0 |
Loss on contracts | 0 | $ 0 | 0 | $ 0 |
Allowance for credit losses | 22,627,000 |  | 22,627,000 |  | $ 18,031,000
Contract asset impairment |  |  | 0 |  | $ 0
Remaining performance obligations | $ 5,378,746,000 |  | 5,378,746,000 |  |
2021 Acquisitions |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |
Increase in contract assets from acquisitions |  |  | 8,800,000 |  |
Increase in contract liabilities from acquisitions |  |  | 24,100,000 |  |
Excluding 2021 Acquisitions |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |
Decrease in net contract liabilities |  |  | $ 30,300,000 |  |

X
- Definition Amount of increase (decrease) in revenue recognized for cumulative catch-up adjustment from change in measure of progress which increases (decreases) right to consideration in exchange for good or service transferred to customer when right is conditioned on something other than passage of time. + References No definition available. + Details
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