Consolidated Statements of Income (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2011
Operating revenues
Drilling - U.S. Land	$ 2,785,449	$ 2,678,475	$ 2,100,508
Drilling - Offshore	221,863	189,086	201,417
Drilling - International Land	366,841	270,027	226,849
Other	13,461	14,214	15,120
Total operating revenues	3,387,614	3,151,802	2,543,894
Operating costs and expenses
Operating costs, excluding depreciation	1,852,768	1,750,510	1,432,602
Depreciation	455,623	387,549	315,468
Research and development	15,235	16,060	15,764
General and administrative	126,250	107,307	91,452
Income from asset sales	(18,923)	(19,223)	(13,903)
Total operating costs and expenses	2,430,953	2,242,203	1,841,383
Operating income from continuing operations	956,661	909,599	702,511
Other income (expense)
Interest and dividend income	1,653	1,380	1,951
Interest expense	(6,129)	(8,653)	(17,355)
Gain on sale of investment securities	162,121		913
Other	(9)	254	(953)
Total other income (expense)	157,636	(7,019)	(15,444)
Income from continuing operations before income taxes	1,114,297	902,580	687,067
Income tax provision	392,844	328,971	252,399
Income from continuing operations	721,453	573,609	434,668
Income (loss) from discontinued operations before income taxes	14,701	7,355	(487)
Income tax provision (benefit)	(485)	(81)	(5)
Income (loss) from discontinued operations	15,186	7,436	(482)
NET INCOME	$ 736,639	$ 581,045	$ 434,186
Basic earnings per common share:
Income from continuing operations (in dollars per share)	$ 6.75	$ 5.35	$ 4.06
Income from discontinued operations (in dollars per share)	$ 0.14	$ 0.07
Net income (in dollars per share)	$ 6.89	$ 5.42	$ 4.06
Diluted earnings per common share:
Income from continuing operations (in dollars per share)	$ 6.65	$ 5.27	$ 3.99
Income from discontinued operations (in dollars per share)	$ 0.14	$ 0.07
Net income (in dollars per share)	$ 6.79	$ 5.34	$ 3.99
Weighted average shares outstanding (in thousands):
Basic (in shares)	106,286	106,819	106,643
Diluted (in shares)	107,879	108,377	108,632