Segment Information (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Sep. 30, 2012
Segment reporting, asset reconciling
Total assets	$ 5,934,288		$ 5,721,085
Revenues from external customers
Total operating revenue	844,572	732,588
Continuing operations
Segment reporting, asset reconciling
Total assets	5,926,500		5,713,466
Discontinuing operations
Segment reporting, asset reconciling
Total assets	7,788		7,619
United States
Revenues from external customers
Total operating revenue	756,485	662,351
Colombia
Revenues from external customers
Total operating revenue	27,405	19,665
Ecuador
Revenues from external customers
Total operating revenue	16,630	12,636
Argentina
Revenues from external customers
Total operating revenue	13,596	12,407
Other Foreign
Revenues from external customers
Total operating revenue	30,456	25,529
Contract Drilling
Segment reporting, asset reconciling
Total assets	5,184,411		5,083,509
Revenues from external customers
Total operating revenue	841,015	729,306
U.S. Land
Segment reporting, asset reconciling
Total assets	4,529,162		4,422,297
Revenues from external customers
Total operating revenue	696,030	617,779
Offshore
Segment reporting, asset reconciling
Total assets	161,086		160,135
Revenues from external customers
Total operating revenue	57,718	50,792
International Land
Segment reporting, asset reconciling
Total assets	461,010		467,538
Revenues from external customers
Total operating revenue	87,267	60,735
Other.
Segment reporting, asset reconciling
Total assets	33,153		33,539
Revenues from external customers
Total operating revenue	3,557	3,282
Reportable and other
Revenues from external customers
Total operating revenue	844,572	732,588
Investments and corporate operations
Segment reporting, asset reconciling
Total assets	$ 742,089		$ 629,957