Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2021	Sep. 30, 2020
Statement Of Financial Position [Abstract]
Property and equipment, accumulated depreciation (in dollars)	$ 741,083	$ 694,709
Intangible assets, excluding goodwill, accumulated amortization (in dollars)	$ 69,511	$ 63,491
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, Authorized shares	500,000,000	500,000,000
Common stock, shares issued	112,949,000	112,824,000
Common stock, shares outstanding	112,679,000	112,405,000
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, Authorized shares	50,000,000	50,000,000
Preferred stock, shares issued	0	0