Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Operating revenues
Contract drilling services	$ 2,785,557	$ 2,474,458	$ 1,792,476
Other	12,933	12,810	12,265
Total operating revenues	2,798,490	2,487,268	1,804,741
Operating costs and expenses
Contract drilling services operating expenses, excluding depreciation and amortization	1,803,204	1,647,557	1,244,735
Operating expenses applicable to other revenues	5,382	5,053	4,582
Depreciation and amortization	562,803	583,802	585,543
Research and development	27,467	18,167	12,047
Selling, general and administrative	194,416	199,257	147,548
Asset impairment charge	224,327	23,128	0
Gain on sale of assets	(39,691)	(22,660)	(20,627)
Total operating costs and expenses	2,777,908	2,454,304	1,973,828
Operating income (loss) from continuing operations	20,582	32,964	(169,087)
Other income (expense)
Interest and dividend income	9,468	8,017	5,915
Interest expense	(25,188)	(24,265)	(19,747)
Gain (loss) on investment securities	(54,488)	1	0
Other	(1,596)	(876)	(1,679)
Total other income (expense)	(71,804)	(17,123)	(15,511)
Income (loss) from continuing operations before income taxes	(51,222)	15,841	(184,598)
Income tax benefit	(18,712)	(477,169)	(56,735)
Income (loss) from continuing operations	(32,510)	493,010	(127,863)
Income from discontinued operations before income taxes	32,848	23,389	3,285
Income tax provision	33,994	33,727	3,634
Loss from discontinued operations	(1,146)	(10,338)	(349)
Net income (loss)	$ (33,656)	$ 482,672	$ (128,212)
Basic earnings (loss) per common share:
Income (loss) from continuing operations (in dollars per share)	$ (0.33)	$ 4.49	$ (1.20)
Loss from discontinued operations (in dollars per share)	(0.01)	(0.10)	0
Net income (loss) (in dollars per share)	(0.34)	4.39	(1.20)
Diluted earnings (loss) per common share:
Income (loss) from continuing operations (in dollars per share)	(0.33)	4.47	(1.20)
Loss from discontinued operations (in dollars per share)	(0.01)	(0.10)	0
Net income (loss) (in dollars per share)	$ (0.34)	$ 4.37	$ (1.20)
Weighted average shares outstanding:
Basic (in shares)	109,216	108,851	108,500
Diluted (in shares)	109,216	109,387	108,500