Business Segment Information (Tables)

12 Months Ended

Sep. 30, 2017

Segment Reporting [Abstract]

Segment Information By Segment

	Year Ended September 30, 2017
	Exploration and Production		Pipeline and Storage		Gathering		Utility		Energy Marketing		Total Reportable Segments		All Other			Corporate and Intersegment Eliminations			Total Consolidated
	(Thousands)
Revenue from External Customers(1)	$	614,599	$	206,615	$	115	$	626,899	$	128,586	$	1,576,814	$	2,173		$	894		$	1,579,881
Intersegment Revenues	$	—	$	87,810	$	107,566	$	13,072	$	794	$	209,242	$	—		$	(209,242	)	$	—
Interest Income	$	707	$	1,467	$	994	$	1,051	$	571	$	4,790	$	213		$	(890	)	$	4,113
Interest Expense	$	53,702	$	33,717	$	9,142	$	28,492	$	47	$	125,100	$	—		$	(5,263	)	$	119,837
Depreciation, Depletion and Amortization	$	112,565	$	41,196	$	16,162	$	52,582	$	279	$	222,784	$	661		$	750		$	224,195
Income Tax Expense (Benefit)	$	66,093	$	40,947	$	29,694	$	24,894	$	891	$	162,519	$	(247	)	$	(1,590	)	$	160,682
Segment Profit: Net Income (Loss)	$	129,326	$	68,446	$	40,377	$	46,935	$	1,509	$	286,593	$	(342	)	$	(2,769	)	$	283,482
Expenditures for Additions to Long-Lived Assets	$	253,057	$	95,336	$	32,645	$	80,867	$	36	$	461,941	$	39		$	137		$	462,117
	At September 30, 2017
	(Thousands)
Segment Assets	$	1,407,152	$	1,929,788	$	580,051	$	2,013,123	$	60,937	$	5,991,051	$	76,861		$	35,408		$	6,103,320

	Year Ended September 30, 2016
	Exploration and Production			Pipeline and Storage		Gathering		Utility		Energy Marketing		Total Reportable Segments			All Other		Corporate and Intersegment Elimination			Total Consolidated
	(Thousands)
Revenue from External Customers(1)	$	607,113		$	215,674	$	374	$	531,024	$	93,578	$	1,447,763		$	3,753	$	900		$	1,452,416
Intersegment Revenues	$	—		$	90,755	$	89,073	$	13,123	$	884	$	193,835		$	—	$	(193,835	)	$	—
Interest Income	$	858		$	770	$	297	$	1,737	$	422	$	4,084		$	117	$	34		$	4,235
Interest Expense	$	55,434		$	33,327	$	8,872	$	27,582	$	49	$	125,264		$	—	$	(4,220	)	$	121,044
Depreciation, Depletion and Amortization	$	139,963		$	43,273	$	15,282	$	48,618	$	278	$	247,414		$	1,260	$	743		$	249,417
Income Tax Expense (Benefit)	$	(334,029	)	$	50,241	$	24,334	$	25,602	$	2,460	$	(231,392	)	$	561	$	(1,718	)	$	(232,549	)
Significant Non-Cash Item: Impairment of Oil and Gas Producing Properties	$	948,307		$	—	$	—	$	—	$	—	$	948,307		$	—	$	—		$	948,307
Segment Profit: Net Income (Loss)	$	(452,842	)	$	76,610	$	30,499	$	50,960	$	4,348	$	(290,425	)	$	778	$	(1,311	)	$	(290,958	)
Expenditures for Additions to Long-Lived Assets	$	256,104		$	114,250	$	54,293	$	98,007	$	34	$	522,688		$	37	$	326		$	523,051
	At September 30, 2016
	(Thousands)
Segment Assets	$	1,323,081		$	1,680,734	$	534,259	$	2,021,514	$	63,392	$	5,622,980		$	77,138	$	(63,731	)	$	5,636,387

	Year Ended September 30, 2015
	Exploration and Production			Pipeline and Storage		Gathering		Utility		Energy Marketing		Total Reportable Segments			All Other			Corporate and Intersegment Eliminations			Total Consolidated
	(Thousands)
Revenue from External Customers(1)	$	693,441		$	203,089	$	497	$	700,761	$	159,857	$	1,757,645		$	2,352		$	916		$	1,760,913
Intersegment Revenues	$	—		$	88,251	$	76,709	$	15,506	$	849	$	181,315		$	—		$	(181,315	)	$	—
Interest Income	$	2,554		$	474	$	140	$	2,220	$	195	$	5,583		$	66		$	(1,727	)	$	3,922
Interest Expense	$	46,726		$	27,658	$	1,627	$	28,176	$	27	$	104,214		$	—		$	(4,743	)	$	99,471
Depreciation, Depletion and Amortization	$	239,818		$	38,178	$	10,829	$	45,616	$	209	$	334,650		$	832		$	676		$	336,158
Income Tax Expense (Benefit)	$	(428,217	)	$	48,113	$	24,721	$	33,143	$	4,547	$	(317,693	)	$	13		$	(1,456	)	$	(319,136	)
Significant Non-Cash Item: Impairment of Oil and Gas Producing Properties	$	1,126,257		$	—	$	—	$	—	$	—	$	1,126,257		$	—		$	—		$	1,126,257
Segment Profit: Net Income (Loss)	$	(556,974	)	$	80,354	$	31,849	$	63,271	$	7,766	$	(373,734	)	$	(2	)	$	(5,691	)	$	(379,427	)
Expenditures for Additions to Long-Lived Assets	$	557,313		$	230,192	$	118,166	$	94,371	$	128	$	1,000,170		$	—		$	339		$	1,000,509
	At September 30, 2015
	(Thousands)
Segment Assets	$	2,439,801		$	1,590,524	$	444,358	$	1,934,731	$	90,676	$	6,500,090		$	77,350		$	(12,501	)	$	6,564,939

(1) All Revenue from External Customers originated in the United States.

Schedule Of Long-Lived Assets, By Geographical Areas

Geographic Information	At September 30
	2017		2016		2015
	(Thousands)
Long-Lived Assets:
United States	$	5,285,040	$	5,223,356	$	6,189,138