Goodwill and Other Intangible Assets (Tables)

12 Months Ended

Sep. 30, 2018

Goodwill And Intangible Assets Disclosure [Abstract]

Summary of Changes in the Company's Goodwill

A summary of changes in the Company’s goodwill during the fiscal years ended September 30, 2018 and 2017 are as follows (in thousands):

Balance as of September 30, 2016	$	212,760
Fiscal year 2017 business combinations		13,155
Balance as of September 30, 2017		225,915
Fiscal year 2018 business combinations		2,521
Balance as of September 30, 2018	$	228,436

Intangible Assets Subject to Amortization

Intangible assets subject to amortization consist of the following (in thousands):

	September 30,
	2018						2017
	Gross						Gross
	Carrying		Accum.				Carrying		Accum.
	Amount		Amortization		Net		Amount		Amortization		Net
Customer lists	$	358,776	$	279,990	$	78,786	$	346,784	$	264,632	$	82,152
Trade names and other intangibles		32,739		13,081		19,658		32,047		8,981		23,066
Total	$	391,515	$	293,071	$	98,444	$	378,831	$	273,613	$	105,218

Estimated Annual Amortization Expense Related to Intangible Assets Subject to Amortization

Total estimated annual amortization expense related to intangible assets subject to amortization, for the year ended September 30, 2019 and the four succeeding fiscal years ended September 30, is as follows (in thousands):

	Amount
2019	$	18,170
2020	$	16,527
2021	$	14,020
2022	$	12,003
2023	$	10,850