Condensed Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Operating revenues
Contract drilling services	$ 314,405	$ 684,788	$ 1,556,093	$ 2,139,798
Other	2,959	3,186	9,567	9,642
Total operating revenues	317,364	687,974	1,565,660	2,149,440
Operating costs and expenses
Contract drilling services operating expenses, excluding depreciation and amortization	205,198	443,114	1,022,270	1,372,426
Other operating expenses	1,549	1,414	4,286	4,308
Depreciation and amortization	110,161	143,297	372,298	427,917
Research and development	3,638	7,066	16,730	21,347
Selling, general and administrative	43,108	46,590	134,894	144,604
Asset impairment charge	0	224,327	563,234	224,327
Restructuring charges	15,495	0	15,495	0
Gain on sale of assets	(4,201)	(9,960)	(18,790)	(27,050)
Total operating costs and expenses	374,948	855,848	2,110,417	2,167,879
Operating loss from continuing operations	(57,584)	(167,874)	(544,757)	(18,439)
Other income (expense)
Interest and dividend income	771	2,349	6,551	6,861
Interest expense	(6,125)	(6,257)	(18,320)	(17,145)
Gain (loss) on investment securities	2,267	(13,271)	(7,325)	(50,228)
Gain on sale of subsidiary	0	0	14,963	0
Other	(2,914)	(1,599)	(3,711)	(1,051)
Total other income (expense)	(6,001)	(18,778)	(7,842)	(61,563)
Loss from continuing operations before income taxes	(63,585)	(186,652)	(552,599)	(80,002)
Income tax benefit	(17,578)	(32,031)	(116,853)	(5,602)
Loss from continuing operations	(46,007)	(154,621)	(435,746)	(74,400)
Income from discontinued operations before income taxes	9,151	7,244	22,675	22,798
Income tax provision	8,743	7,306	22,463	23,231
Income (loss) from discontinued operations	408	(62)	212	(433)
Net loss	$ (45,599)	$ (154,683)	$ (435,534)	$ (74,833)
Basic loss per common share:
Loss from continuing operations (in dollars per share)	$ (0.43)	$ (1.42)	$ (4.05)	$ (0.71)
Loss from discontinued operations (in dollars per share)	0	0	0	0
Net loss (in dollars per share)	(0.43)	(1.42)	(4.05)	(0.71)
Diluted loss per common share:
Loss from continuing operations (in dollars per share)	(0.43)	(1.42)	(4.05)	(0.71)
Loss from discontinued operations (in dollars per share)	0	0	0	0
Net loss (in dollars per share)	$ (0.43)	$ (1.42)	$ (4.05)	$ (0.71)
Weighted average shares outstanding:
Basic (in shares)	107,439	109,425	108,185	109,324
Diluted (in shares)	107,439	109,425	108,185	109,324