Intangible Assets Subject to Amortization (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Sep. 30, 2018
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 420,112	$ 391,515
Accum. Amortization	312,424	293,071
Net	107,688	98,444
Customer Lists
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	382,373	358,776
Accum. Amortization	297,221	279,990
Net	85,152	78,786
Trade Names And Other Intangibles
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	37,739	32,739
Accum. Amortization	15,203	13,081
Net	$ 22,536	$ 19,658

Accumulated amount of amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16323-109275

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Amount before amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 928
-SubTopic 340
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6473545&loc=d3e61844-108004

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16323-109275

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Amount after amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16323-109275

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