GUARANTOR AND NON-GUARANTOR FINANCIAL INFORMATION - Cash Flows (Details) - USD ($) $ in Thousands	9 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
CONDENSED CONSOLIDATING STATEMENTS OF CASH FLOWS
Net cash provided by (used in) operating activities	$ 659,371	$ 371,428
Cash flows from investing activities:
Capital expenditures	(403,570)	(322,658)
Purchase of short-term investments	(71,852)	(52,159)
Payment for acquisition of business, net of cash acquired	(2,781)	(47,886)
Proceeds from sale of short-term investments	68,015	52,470
Intercompany transfers	0	0
Proceeds from asset sales	36,227	28,049
Net cash used in investing activities	(373,961)	(342,184)
Cash flows from financing activities:
Intercompany transfers	0	0
Dividends paid	(235,058)	(230,368)
Debt issuance costs paid	(3,912)	0
Payments for employee taxes on net settlement of equity awards	(6,420)	(5,978)
Proceeds from stock option exercises	2,901	5,160
Other intercompany transfers	0
Payment of contingent consideration from acquisition of business	0	(10,625)
Net cash used in financing activities	(242,489)	(241,811)
Net increase (decrease) in cash and cash equivalents and restricted cash	42,921	(212,567)
Cash and cash equivalents and restricted cash, beginning of period	326,185	560,509
Cash and cash equivalents and restricted cash, end of period	369,106	347,942
Eliminations
CONDENSED CONSOLIDATING STATEMENTS OF CASH FLOWS
Net cash provided by (used in) operating activities	0	0
Cash flows from investing activities:
Capital expenditures	0	0
Purchase of short-term investments	0	0
Payment for acquisition of business, net of cash acquired	0	0
Proceeds from sale of short-term investments	0	0
Intercompany transfers	0	0
Proceeds from asset sales	0	0
Net cash used in investing activities	0	0
Cash flows from financing activities:
Intercompany transfers	0	0
Dividends paid	0	0
Debt issuance costs paid	0
Payments for employee taxes on net settlement of equity awards	0	0
Proceeds from stock option exercises	0	0
Other intercompany transfers	0
Payment of contingent consideration from acquisition of business		0
Net cash used in financing activities	0	0
Net increase (decrease) in cash and cash equivalents and restricted cash	0	0
Cash and cash equivalents and restricted cash, beginning of period	0	0
Cash and cash equivalents and restricted cash, end of period	0	0
Helmerich & Payne, Inc. (Guarantor) | Reportable Legal Entities
CONDENSED CONSOLIDATING STATEMENTS OF CASH FLOWS
Net cash provided by (used in) operating activities	(15,599)	1,914
Cash flows from investing activities:
Capital expenditures	(7,355)	(8,725)
Purchase of short-term investments	0	0
Payment for acquisition of business, net of cash acquired	(2,781)	(47,886)
Proceeds from sale of short-term investments	0	0
Intercompany transfers	7,355	56,611
Proceeds from asset sales	6	0
Net cash used in investing activities	(2,775)	0
Cash flows from financing activities:
Intercompany transfers	235,058	230,368
Dividends paid	(235,058)	(230,368)
Debt issuance costs paid	(3,912)
Payments for employee taxes on net settlement of equity awards	(6,420)	(5,978)
Proceeds from stock option exercises	2,901	5,160
Other intercompany transfers	111,339
Payment of contingent consideration from acquisition of business		0
Net cash used in financing activities	103,908	(818)
Net increase (decrease) in cash and cash equivalents and restricted cash	85,534	1,096
Cash and cash equivalents and restricted cash, beginning of period	6,037	9,385
Cash and cash equivalents and restricted cash, end of period	91,571	10,481
Helmerich & Payne International Drilling Co. (Issuer) | Reportable Legal Entities
CONDENSED CONSOLIDATING STATEMENTS OF CASH FLOWS
Net cash provided by (used in) operating activities	657,016	350,557
Cash flows from investing activities:
Capital expenditures	(389,615)	(306,278)
Purchase of short-term investments	(70,175)	(52,159)
Payment for acquisition of business, net of cash acquired	0	0
Proceeds from sale of short-term investments	68,015	52,470
Intercompany transfers	(7,355)	(56,611)
Proceeds from asset sales	32,585	26,737
Net cash used in investing activities	(366,545)	(335,841)
Cash flows from financing activities:
Intercompany transfers	(235,058)	(230,368)
Dividends paid	0	0
Debt issuance costs paid	0
Payments for employee taxes on net settlement of equity awards	0	0
Proceeds from stock option exercises	0	0
Other intercompany transfers	(103,788)
Payment of contingent consideration from acquisition of business		0
Net cash used in financing activities	(338,846)	(230,368)
Net increase (decrease) in cash and cash equivalents and restricted cash	(48,375)	(215,652)
Cash and cash equivalents and restricted cash, beginning of period	273,214	507,504
Cash and cash equivalents and restricted cash, end of period	224,839	291,852
Non-Guarantor Subsidiaries | Reportable Legal Entities
CONDENSED CONSOLIDATING STATEMENTS OF CASH FLOWS
Net cash provided by (used in) operating activities	17,954	18,957
Cash flows from investing activities:
Capital expenditures	(6,600)	(7,655)
Purchase of short-term investments	(1,677)	0
Payment for acquisition of business, net of cash acquired	0	0
Proceeds from sale of short-term investments	0	0
Intercompany transfers	0	0
Proceeds from asset sales	3,636	1,312
Net cash used in investing activities	(4,641)	(6,343)
Cash flows from financing activities:
Intercompany transfers	0	0
Dividends paid	0	0
Debt issuance costs paid	0
Payments for employee taxes on net settlement of equity awards	0	0
Proceeds from stock option exercises	0	0
Other intercompany transfers	(7,551)
Payment of contingent consideration from acquisition of business		(10,625)
Net cash used in financing activities	(7,551)	(10,625)
Net increase (decrease) in cash and cash equivalents and restricted cash	5,762	1,989
Cash and cash equivalents and restricted cash, beginning of period	46,934	43,620
Cash and cash equivalents and restricted cash, end of period	$ 52,696	$ 45,609