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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

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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.

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