Commitments and Contingencies (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Sep. 30, 2017
Operating Leased Assets [Line Items]
Rent expense	$ 4,091	$ 4,777	$ 13,843	$ 13,608
Letters of credit outstanding, amount	13,244		13,244		$ 17,274
Equipment [Member]
Operating Leased Assets [Line Items]
Capital leased assets, gross	50,005		50,005		43,727
Capital leases, carrying value	30,077		30,077		30,302
Letter of Credit [Member]
Operating Leased Assets [Line Items]
Letters of credit outstanding, amount	13,157		13,157		6,706
Surety Bond [Member]
Operating Leased Assets [Line Items]
Surety bonds	100,487		100,487		87,849
Siemens [Member]
Operating Leased Assets [Line Items]
Letters of credit outstanding, amount	867		867		901
Siemens [Member] | Surety Bond [Member]
Operating Leased Assets [Line Items]
Surety bonds	$ 5,545		$ 5,545		$ 12,970
Minimum [Member]
Operating Leased Assets [Line Items]
Lessor, operating lease, term of contract			5 years
Minimum [Member] | Surety Bond [Member]
Operating Leased Assets [Line Items]
Financial instruments, commitments, expiration period			12 months
Maximum [Member]
Operating Leased Assets [Line Items]
Lessor, operating lease, term of contract			20 years
Maximum [Member] | Surety Bond [Member]
Operating Leased Assets [Line Items]
Financial instruments, commitments, expiration period			10 years