Impact on Previously Issued Financial Statements for Immaterial Adjustments - Summary of Revised Consolidated Balance Sheet (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019
ASSETS
Total current assets	$ 271,739		$ 250,105
Total assets	1,709,039		1,687,617
LIABILITIES AND STOCKHOLDERS' EQUITY
Total current liabilities	168,882		198,631
Total liabilities	687,190		727,546
Total stockholders' equity	1,021,849	$ 1,003,441	960,071	$ 939,618	$ 937,175	$ 1,068,128
Total liabilities and stockholders' equity	$ 1,709,039		1,687,617
As Reported
ASSETS
Total current assets			249,148
Total assets			1,687,445
LIABILITIES AND STOCKHOLDERS' EQUITY
Total current liabilities			200,774
Total liabilities			729,689
Total stockholders' equity			957,756
Total liabilities and stockholders' equity			1,687,445
Adjustment
ASSETS
Total current assets			957
Total assets			172
LIABILITIES AND STOCKHOLDERS' EQUITY
Total current liabilities			(2,143)
Total liabilities			(2,143)
Total stockholders' equity			2,315
Total liabilities and stockholders' equity			$ 172