Guarantor and Non-Guarantor Financial Information - Statement of Income (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
CONSOLIDATED CONDENSED STATEMENTS OF OPERATIONS
Operating revenue	$ 368,590	$ 487,847
Operating costs and other	417,754	449,177
Operating income (loss) from continuing operations	(49,164)	38,670
Other income, net	1,377	472
Interest expense	(5,055)	(4,524)
Income (loss) from continuing operations before income taxes	(52,842)	34,618
Income tax provision	(18,288)	18,720
Income (loss) from continuing operations	(34,554)	15,898
Income (loss) from discontinued operations before income taxes	(424)	104
Income tax provision	85
Income (loss) from discontinued operations	(509)	104
NET INCOME (LOSS)	(35,063)	16,002
Eliminations
CONSOLIDATED CONDENSED STATEMENTS OF OPERATIONS
Operating revenue	(17)	(17)
Operating costs and other	(231)	(401)
Operating income (loss) from continuing operations	214	384
Other income, net	(214)	(384)
Equity in net income (loss) of subsidiaries	32,663	(9,352)
Income (loss) from continuing operations before income taxes	32,663	(9,352)
Income (loss) from continuing operations	32,663	(9,352)
NET INCOME (LOSS)	32,663	(9,352)
Guarantor/Parent | Reportable Legal Entities
CONSOLIDATED CONDENSED STATEMENTS OF OPERATIONS
Operating costs and other	3,460	2,705
Operating income (loss) from continuing operations	(3,460)	(2,705)
Other income, net		20
Interest expense	(86)	(62)
Equity in net income (loss) of subsidiaries	(32,992)	17,549
Income (loss) from continuing operations before income taxes	(36,538)	14,802
Income tax provision	(1,475)	(1,200)
Income (loss) from continuing operations	(35,063)	16,002
NET INCOME (LOSS)	(35,063)	16,002
Issuer Subsidiary | Reportable Legal Entities
CONSOLIDATED CONDENSED STATEMENTS OF OPERATIONS
Operating revenue	297,448	405,537
Operating costs and other	339,502	356,751
Operating income (loss) from continuing operations	(42,054)	48,786
Other income, net	1,019	656
Interest expense	(4,709)	(4,718)
Equity in net income (loss) of subsidiaries	329	(8,197)
Income (loss) from continuing operations before income taxes	(45,415)	36,527
Income tax provision	(12,550)	19,227
Income (loss) from continuing operations	(32,865)	17,300
NET INCOME (LOSS)	(32,865)	17,300
Non-Guarantor Subsidiaries | Reportable Legal Entities
CONSOLIDATED CONDENSED STATEMENTS OF OPERATIONS
Operating revenue	71,159	82,327
Operating costs and other	75,023	90,122
Operating income (loss) from continuing operations	(3,864)	(7,795)
Other income, net	572	180
Interest expense	(260)	256
Income (loss) from continuing operations before income taxes	(3,552)	(7,359)
Income tax provision	(4,263)	693
Income (loss) from continuing operations	711	(8,052)
Income (loss) from discontinued operations before income taxes	(424)	104
Income tax provision	85
Income (loss) from discontinued operations	(509)	104
NET INCOME (LOSS)	$ 202	$ (7,948)