CONSOLIDATED STATEMENTS OF OPERATIONS (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2011
REVENUES:
Contract drilling	$ 1,017,923	$ 755,969	$ 637,199
Revenues related to reimbursable expenses	45,740	31,452	7,877
Total revenues	1,063,663	787,421	645,076
COSTS AND EXPENSES:
Contract drilling	426,198	328,485	218,883
Reimbursable expenses	32,727	18,694	4,682
Depreciation	117,510	70,599	43,597
General and administrative	56,786	49,776	44,407
Other, net	971	457	4,847
Total costs and expenses	634,192	468,011	316,416
OPERATING INCOME	429,471	319,410	328,660
OTHER INCOME (EXPENSE):
Interest expense, net of capitalized interest	(24,903)	(6,460)	(4,530)
Interest income	233	354	717
Other income (expense) total	(24,670)	(6,106)	(3,813)
INCOME BEFORE INCOME TAXES	404,801	313,304	324,847
PROVISION FOR INCOME TAXES	54,577	41,133	53,173
NET INCOME	$ 350,224	$ 272,171	$ 271,674
EARNINGS PER COMMON SHARE (NOTE 2):
Basic (in dollars per share)	$ 5.38	$ 4.17	$ 4.20
Diluted (in dollars per share)	$ 5.32	$ 4.14	$ 4.15
WEIGHTED AVERAGE COMMON SHARES OUTSTANDING (NOTE 2):
Basic (in shares)	65,073	65,267	64,754
Diluted (in shares)	65,845	65,781	65,403