Goodwill - Changes in the Carrying Value of Goodwill (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
Sep. 30, 2020	Dec. 31, 2020	Dec. 31, 2019
Changes in the carrying value of goodwill:
Acquisition goodwill recognized		$ 17,522
Measurement period adjustment		2,276
Goodwill impairment recognized	$ (11,700)	(11,706)	$ 0
Goodwill		19,798
Accumulated impairment losses		(11,706)
Goodwill balance, net of impairment		$ 8,092	$ 0

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 before 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 accumulated impairment loss for 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 loss from the write-down 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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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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