Summary of Significant Accounting Policies - Revenue Recognition (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Sep. 30, 2019
Impact due to new accounting pronouncements
Adjustment to increase retained earnings	$ 778,398	$ 684,741
Effect of the adoption of ASC 606 \| ASU 2014-09
Impact due to new accounting pronouncements
Adjustment to increase retained earnings		$ 5,200

The cumulative amount of the reporting entity's undistributed earnings or deficit.

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