Intangible Assets Subject to Amortization (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Sep. 30, 2016
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 378,831	$ 354,522
Accum. Amortization	273,613	256,866
Net	105,218	97,656
Customer Lists
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	346,784	327,388
Accum. Amortization	264,632	250,427
Net	82,152	76,961
Trade Names And Other Intangibles
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	32,047	27,134
Accum. Amortization	8,981	6,439
Net	$ 23,066	$ 20,695

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/presentationRef
-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.

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

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