Commitments and Contingencies (Details) - USD ($) $ in Thousands	1 Months Ended
	Jul. 31, 2016	Mar. 31, 2018	Sep. 30, 2017
Loss Contingencies [Line Items]
Accounts receivable, net of allowance for doubtful accounts of $746 and $1,062 at March 31, 2018 and September 30, 2017, respectively		$ 127,151	$ 152,299
Pending Litigation
Loss Contingencies [Line Items]
Loss contingency accrual		1,200
Korea
Loss Contingencies [Line Items]
Income tax examination, estimate of possible loss	$ 12,000
Minimum | Pending Litigation
Loss Contingencies [Line Items]
Loss Contingency, Estimate of Possible Loss		1,200
Minimum | Customer Contracts
Loss Contingencies [Line Items]
Accounts receivable, net of allowance for doubtful accounts of $746 and $1,062 at March 31, 2018 and September 30, 2017, respectively		0
Maximum | Pending Litigation
Loss Contingencies [Line Items]
Loss Contingency, Estimate of Possible Loss		3,400
Maximum | Customer Contracts
Loss Contingencies [Line Items]
Accounts receivable, net of allowance for doubtful accounts of $746 and $1,062 at March 31, 2018 and September 30, 2017, respectively		$ 17,300