Pension and Retirement Plans (Detail) - Amounts recognized in the consolidated balance sheet - USD ($) $ in Thousands	Sep. 30, 2017	Sep. 30, 2016
Defined Benefit Plan Disclosure [Line Items]
Accrued benefit liability	$ (12,352)	$ (14,022)
Deferred tax	(383)	(150)
Accumulated other comprehensive income	6,949	9,124
Net amount recognized	(5,786)	(5,048)
Accumulated benefit obligation	(20,446)	(21,482)
Pension
Defined Benefit Plan Disclosure [Line Items]
Accrued benefit liability	(11,097)	(12,765)
Deferred tax	(474)	(202)
Accumulated other comprehensive income	6,911	9,027
Net amount recognized	(4,660)	(3,940)
Accumulated benefit obligation	(19,191)	(20,225)
Post Retirement
Defined Benefit Plan Disclosure [Line Items]
Accrued benefit liability	(1,255)	(1,257)
Deferred tax	91	52
Accumulated other comprehensive income	38	97
Net amount recognized	(1,126)	(1,108)
Accumulated benefit obligation	(1,255)	(1,257)
International
Defined Benefit Plan Disclosure [Line Items]
Accrued benefit liability	(10,420)	(11,936)
Deferred tax	(493)	(216)
Accumulated other comprehensive income	6,893	9,001
Net amount recognized	(4,020)	(3,151)
Accumulated benefit obligation	(18,514)	(19,396)
International | Pension
Defined Benefit Plan Disclosure [Line Items]
Accrued benefit liability	(10,420)	(11,936)
Deferred tax	(493)	(216)
Accumulated other comprehensive income	6,893	9,001
Net amount recognized	(4,020)	(3,151)
Accumulated benefit obligation	(18,514)	(19,396)
International | Post Retirement
Defined Benefit Plan Disclosure [Line Items]
Accrued benefit liability	0	0
Deferred tax	0	0
Accumulated other comprehensive income	0	0
Net amount recognized	0	0
Accumulated benefit obligation	0	0
Domestic
Defined Benefit Plan Disclosure [Line Items]
Accrued benefit liability	(1,932)	(2,086)
Deferred tax	110	66
Accumulated other comprehensive income	56	123
Net amount recognized	(1,766)	(1,897)
Accumulated benefit obligation	(1,932)	(2,086)
Domestic | Pension
Defined Benefit Plan Disclosure [Line Items]
Accrued benefit liability	(677)	(829)
Deferred tax	19	14
Accumulated other comprehensive income	18	26
Net amount recognized	(640)	(789)
Accumulated benefit obligation	(677)	(829)
Domestic | Post Retirement
Defined Benefit Plan Disclosure [Line Items]
Accrued benefit liability	(1,255)	(1,257)
Deferred tax	91	52
Accumulated other comprehensive income	38	97
Net amount recognized	(1,126)	(1,108)
Accumulated benefit obligation	$ (1,255)	$ (1,257)