Summary of Significant Accounting Policies (Tables)

12 Months Ended

Sep. 30, 2019

Accounting Policies [Abstract]

Summary of depreciable lives of property, plant and equipment

Buildings	10 - 40 years
Computer equipment and software	3 - 7 years
Machinery and equipment	2 - 10 years
Furniture and fixtures	3 - 10 years

Summary of amortizable lives of finite-lived intangible assets

Patents	7 - 15 years
Completed technology	3 - 15 years
Customer relationships	3 - 14 years

Summary of stock-based compensation expense

	Year Ended September 30,
	2019		2018		2017
Restricted stock units	$	18,276	$	18,081	$	16,056
Employee stock purchase plan		1,203		775		517
Total stock-based compensation expense	$	19,479	$	18,856	$	16,573

Summary of valuation assumptions for an employee stock purchase plan

	Year Ended September 30,
	2019		2018		2017
Risk-free interest rate	2.3	%	1.9	%	0.9	%
Volatility	52	%	46	%	34	%
Expected life	6 months		6 months		6 months
Dividend yield	1.2	%	1.5	%	3.4	%

Schedule of cumulative effect of adoption

	As Reported		Impact of Adopting		As Adopted
	September 30, 2018		ASC 606		October 1, 2018
Prepaid expenses and other current assets	$	31,741	$	350	$	32,091
Prepaid expenses and other current assets - discontinued operations		343		235		578
Other assets		5,294		1,483		6,777
Long-term deferred tax assets		43,798		403		44,201
Deferred revenue		25,884		2,850		28,734
Deferred revenue - discontinued operations		1,052		480		1,532
Accumulated deficit		(994,074)		(859)		(994,933)

		Year Ended September 30, 2019
			Without adoption of		Effect of Change
	As Reported		ASC 606		Higher/(Lower)
Revenue	$	780,848	$	781,714	$	(866)
Cost of revenue		464,588		466,425		(1,837)
Gross profit		316,260		315,289		971
Operating expenses		270,222		269,559		663
Operating income	$	46,038	$	45,730	$	308

		September 30, 2019
			Without adoption of		Effect of Change
	As Reported		ASC 606		Higher/(Lower)
Prepaid expenses and other current assets	$	46,332	$	42,294	$	4,038
Other assets		20,506		19,686		820
Deferred revenue		29,435		27,390		2,045
Accumulated deficit		(586,412)		(589,225)		2,813