Revenue Recognition - Balance Sheet Impact of Adoption of ASC 606 (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Sep. 30, 2018
ASSETS
Accounts receivable – net	$ 728,999	$ 694,221
Contract assets	145,672	142,882
Deferred tax assets	30,572	8,607
LIABILITIES AND EQUITY
Contract liabilities	147,549	143,270
Income taxes payable	56	8,272
Equity:
Retained earnings	1,067,851	$ 944,965
Recognition Under Previous Guidance
ASSETS
Accounts receivable – net	737,107
Contract assets	147,947
Deferred tax assets	29,452
LIABILITIES AND EQUITY
Contract liabilities	154,704
Income taxes payable	(126)
Equity:
Retained earnings	1,070,140
Impact of the Adoption of ASC 606 \| Accounting Standards Update 2014-09
ASSETS
Accounts receivable – net	(8,108)
Contract assets	(2,275)
Deferred tax assets	1,120
LIABILITIES AND EQUITY
Contract liabilities	(7,155)
Income taxes payable	182
Equity:
Retained earnings	$ (2,289)

Amount due from customers or clients, within one year of the balance sheet date (or the normal operating cycle, whichever is longer), for goods or services (including trade receivables) that have been delivered or sold in the normal course of business, reduced to the estimated net realizable fair value by an allowance established by the entity of the amount it deems uncertain of collection.

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