CONSOLIDATED CONDENSED STATEMENTS OF INCOME (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2013	Mar. 31, 2012
Operating revenues:
Drilling - U.S. Land	$ 685,710	$ 658,804	$ 1,381,740	$ 1,276,583
Drilling - Offshore	55,605	43,421	113,323	94,213
Drilling - International Land	94,092	64,088	181,359	124,823
Other	2,902	3,669	6,459	6,951
Total operating revenues	838,309	769,982	1,682,881	1,502,570
Operating costs and other:
Operating costs, excluding depreciation	461,737	448,208	928,608	839,240
Depreciation	112,433	90,934	219,032	177,222
General and administrative	32,836	27,805	65,257	53,968
Research and development	3,696	3,830	7,049	7,079
Income from asset sales	(5,313)	(7,820)	(10,532)	(12,503)
Total operating costs and expenses	605,389	562,957	1,209,414	1,065,006
Operating income from continuing operations	232,920	207,025	473,467	437,564
Other income (expense):
Interest and dividend income	315	356	741	692
Interest expense	(1,186)	(2,421)	(2,494)	(4,882)
Gain from sale of investment securities			8,752
Other	103	(42)	(1,981)	(21)
Total other income (expense)	(768)	(2,107)	5,018	(4,211)
Income from continuing operations before income taxes	232,152	204,918	478,485	433,353
Income tax provision	81,085	75,155	167,807	159,293
Income from continuing operations	151,067	129,763	310,678	274,060
Loss from discontinued operations before income taxes	(472)	(125)	(480)	(136)
Income tax provision	(485)	(81)	(485)	(81)
Income (loss) from discontinued operations	13	(44)	5	(55)
NET INCOME	$ 151,080	$ 129,719	$ 310,683	$ 274,005
Basic earnings per common share:
Income from continuing operations (in dollars per share)	$ 1.41	$ 1.20	$ 2.91	$ 2.54
Net income (in dollars per share)	$ 1.41	$ 1.20	$ 2.91	$ 2.54
Diluted earnings per common share:
Income from continuing operations (in dollars per share)	$ 1.39	$ 1.18	$ 2.87	$ 2.51
Net income (in dollars per share)	$ 1.39	$ 1.18	$ 2.87	$ 2.51
Weighted average shares outstanding:
Basic (in shares)	106,326	107,385	106,094	107,285
Diluted (in shares)	107,786	109,042	107,640	108,925
Dividends declared per common share (in dollars per share)	$ 0.15	$ 0.07	$ 0.30	$ 0.14