Basis of Presentation and Summary of Significant Accounting Policies (Details 3) - USD ($) $ in Thousands	3 Months Ended									12 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Equity Method Investment
Equity method investment impairment charge		$ 3,000								$ 2,966	$ 0	$ 0
Equity method investment, other than temporary impairment, net of tax										2,966	0	0
Decrease of equity method investment due to foreign currency translation loss										300
Shipping and Handling Costs
Net sales	$ 432,291		$ 442,374	$ 426,474	$ 395,311	$ 406,817	$ 410,359	$ 390,183	$ 363,091	1,696,450	1,570,450	1,429,429
Cost of sales										1,293,357	1,167,294	1,067,522
Foreign Currency Translation
Foreign currency transaction gains and (losses)										$ (800)	$ 300	$ 100
Minimum
Revenue from Contract with Customer
Purchase contract term										3 years
Revenue, performance obligation, payment terms										30 days
Maximum
Revenue from Contract with Customer
Purchase contract term										5 years
Revenue, performance obligation, payment terms										90 days
Consigned inventory fixed fees as a percentage of consolidated revenues										1.00%
Cost of goods total \| Supplier concentration risk \| Precision Castparts Corporation
Concentration Risk [Line Items]
Concentration risk										9.00%	12.00%	13.00%
Cost of goods total \| Supplier concentration risk \| Alcoa Fastening Systems
Concentration Risk [Line Items]
Concentration risk										8.00%	8.00%	9.00%
Accounts payable \| Supplier concentration risk \| Precision Castparts Corporation
Concentration Risk [Line Items]
Concentration risk										3.00%	4.00%
Accounts payable \| Supplier concentration risk \| Alcoa Fastening Systems
Concentration Risk [Line Items]
Concentration risk										3.00%	6.00%
Sales revenue \| Customer concentration risk
Concentration Risk [Line Items]
Concentration risk										13.00%	11.00%	11.00%
Accounts receivable \| Customer concentration risk \| U.S. Defense Logistics Agency or Defense Contractors
Concentration Risk [Line Items]
Concentration risk										16.00%	14.00%	16.00%
Shipping and Handling
Shipping and Handling Costs
Net sales										$ 4,400	$ 3,900	$ 4,600
Cost of sales										38,500	33,500	$ 31,400
APAC
Equity Method Investment
Carrying value of equity investment	$ 7,100									$ 7,100	$ 10,400

Wesco Aircraft Holdings, Inc 10-K