Stock-Based Compensation (Tables)

6 Months Ended

Mar. 31, 2021

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Summary of stock-based compensation expense

	Three Months Ended March 31,				Six Months Ended March 31,
	2021		2020		2021		2020
Restricted stock units	$	7,048	$	3,921	$	13,192	$	8,014
Employee stock purchase plan		433		293		999		610
Total stock-based compensation expense	$	7,481	$	4,214	$	14,191	$	8,624

Restricted Stock Unit Activity

		Time-Based	Stock	Performance-
	Total Units	Units	Grants	Based Units
Six months ended March 31, 2021	329,801	149,249	14,657	165,895
Six months ended March 31, 2020	408,827	163,390	23,867	221,570

		Weighted
		Average
		Grant-Date
	Shares	Fair Value
Outstanding at September 30, 2020	1,183,009	$	36.10
Granted	329,801		70.18
Vested	(403,832)		36.08
Forfeited	(30,051)		42.91
Outstanding at March 31, 2021	1,078,927		46.33