SUPPLEMENTAL BALANCE SHEET INFORMATION (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Reserve for bad debt:
Balance at the beginning of the period	$ 6,181	$ 4,597	$ 4,795
Provision for (recovery of) bad debt	(2,013)	6,034	(200)
Write off of bad debt	(1,472)	(4,450)	2
Balance at the end of the period	2,696	6,181	$ 4,597
Accounts receivable, net of reserve:
Trade receivables	286,998	445,948
Insurance recovery receivable	50,200
Income tax receivable	37,971
Total accounts receivable, net of reserve	375,169	445,948
Prepaid expenses and other current assets:
Restricted cash	27,566	28,484
Prepaid insurance	4,354	6,386
Deferred mobilization	9,913	11,697
Prepaid income taxes	26,138	6,867
Prepaid value added tax	1,407	1,055
Other	8,689	9,986
Total prepaid expenses and other current assets	78,067	64,475
Accrued liabilities:
Accrued operating costs	17,009	34,292
Payroll and employee benefits	43,547	36,101
Taxes payable, other than income tax	31,443	38,571
Deferred mobilization	17,923	18,230
Self-insurance liabilities	14,801	10,796
Deferred income	34,681	42,769
Other	4,700	16,798
Litigation and claims	70,535
Total accrued liabilities	234,639	197,557
Noncurrent liabilities - Other:
Pension and other non-qualified retirement plans	39,762	28,423
Self-insurance liabilities	21,651	20,846
Deferred mobilization	24,781	38,492
Uncertain tax positions including interest and penalties	12,502	17,724
Other	4,085	4,635
Total noncurrent liabilities - other	$ 102,781	$ 110,120