Goodwill and Other Intangible Assets (Schedule of Goodwill) (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
Sep. 30, 2021	Dec. 31, 2020
Goodwill [Roll Forward]
Goodwill	$ 1,237,894	$ 1,191,259
Acquisitions		46,624
Acquisition fair value adjustment	196	11
Goodwill	$ 1,238,090	$ 1,237,894

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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Amount of increase in asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized resulting from a business combination.

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Amount of increase (decrease) from adjustments after acquisition date under purchase accounting of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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