Leases - Other Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Leases
Operating lease - cash paid for fixed payments	$ 5,100	$ 4,600	$ 9,900	$ 9,100
Finance lease - cash paid for finance lease liabilities	673		691
Right-of-use assets obtained in exchange for new finance lease liabilities	400		13,000
Right-of-use assets obtained in exchange for new operating lease liabilities	$ 2,800	$ 8,400	$ 3,000	$ 18,000