Condensed Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2019	Mar. 31, 2018
Operating revenues
Operating revenues	$ 720,868	$ 577,484	$ 1,461,466	$ 1,141,571
Operating costs and expenses
Contract drilling operating expenses, excluding depreciation and amortization	441,719	384,419	929,312	756,335
Operating expenses applicable to other revenues	1,620	1,137	2,894	2,304
Depreciation and amortization	143,161	145,675	284,620	288,942
Research and development	7,262	4,436	14,281	7,670
Selling, general and administrative	43,506	48,236	98,014	94,695
Gain on sale of assets	(11,546)	(5,255)	(17,090)	(10,820)
Total operating costs and expenses	625,722	578,648	1,312,031	1,139,126
Operating income (loss) from continuing operations	95,146	(1,164)	149,435	2,445
Other income (expense)
Interest and dividend income	2,061	1,847	4,512	3,571
Interest expense	(6,167)	(6,028)	(10,888)	(11,801)
Gain (loss) on investment securities	5,878		(36,957)
Other	17	(210)	548	231
Total other income (expense)	1,789	(4,391)	(42,785)	(7,999)
Income (loss) from continuing operations before income taxes	96,935	(5,555)	106,650	(5,554)
Income tax provision (benefit)	25,078	(3,922)	26,429	(504,563)
Income (loss) from continuing operations	71,857	(1,633)	80,221	499,009
Income from discontinued operations before income taxes	2,889	1,263	15,554	744
Income tax provision	13,855	11,509	15,925	11,526
Loss from discontinued operations	(10,966)	(10,246)	(371)	(10,782)
Net income (loss)	$ 60,891	$ (11,879)	$ 79,850	$ 488,227
Basic earnings (loss) per common share:
Income (loss) from continuing operations (in dollars per share)	$ 0.65	$ (0.03)	$ 0.72	$ 4.55
Loss from discontinued operations (in dollars per share)	(0.10)	(0.09)		(0.10)
Net income (loss) (in dollars per share)	0.55	(0.12)	0.72	4.45
Diluted earnings (loss) per common share:
Income (loss) from continuing operations (in dollars per share)	0.65	(0.03)	0.72	4.53
Loss from discontinued operations (in dollars per share)	(0.10)	(0.09)		(0.10)
Net income (loss) (in dollars per share)	$ 0.55	$ (0.12)	$ 0.72	$ 4.43
Weighted average shares outstanding (in thousands):
Basic (in shares)	109,406	108,868	109,273	108,775
Diluted (in shares)	109,503	108,868	109,452	109,212
Contract Drilling
Operating revenues
Operating revenues	$ 717,653	$ 574,471	$ 1,455,011	$ 1,135,540
Other.
Operating revenues
Operating revenues	$ 3,215	$ 3,013	$ 6,455	$ 6,031