BUSINESS SEGMENT AND GEOGRAPHIC INFORMATION - Total assets (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Sep. 30, 2018
Segment information
Assets	$ 6,144,562	$ 6,214,867
Operating segment
Segment information
Assets	5,686,992	5,656,332
Investments and corporate operations
Segment information
Assets	457,570	558,535
U.S. Land | Operating segment
Segment information
Assets	5,090,206	5,012,378
Offshore | Operating segment
Segment information
Assets	94,627	105,439
International Land | Operating segment
Segment information
Assets	318,600	362,033
H&P Technologies | Operating segment
Segment information
Assets	153,216	146,957
Other.. | Operating segment
Segment information
Assets	30,343	29,525
Continued operations
Segment information
Assets	$ 6,144,562	$ 6,214,867