Retirement and Post-Retirement Employee Benefit Plans (Table)

12 Months Ended

Sep. 30, 2016

Compensation and Retirement Disclosure [Abstract]

Schedule of Net Periodic Benefit Cost Not Yet Recognized And Recorded as Regulatory Assets

The amounts that have not yet been recognized in net periodic pension cost that have been recorded as regulatory assets are as follows:

	Defined Benefits Plan			Supplemental Executive Retirement Plans		Postretirement Plans			Total
	(In thousands)
September 30, 2016
Unrecognized prior service credit	$	(1,509	)	$	—	$	(2,880	)	$	(4,389	)
Unrecognized actuarial (gain) loss	127,028			51,558		(54,298		)	124,288
	$	125,519		$	51,558	$	(57,178	)	$	119,899
September 30, 2015
Unrecognized transition obligation	$	—		$	—	$	82		$	82
Unrecognized prior service credit	(1,735		)	—		(4,524		)	(6,259		)
Unrecognized actuarial (gain) loss	120,948			36,915		(47,149		)	110,714
	$	119,213		$	36,915	$	(51,591	)	$	104,537

Schedule of Allocation of Plan Assets

The following table presents asset allocation information for the postretirement benefit plan assets as of September 30, 2016 and 2015.

	Actual Allocation September 30
Security Class	2016		2015
Diversified investment funds	97.2	%	97.5	%
Cash and cash equivalents	2.8	%	2.5	%

The following table presents asset allocation information for the Master Trust as of September 30, 2016 and 2015.

	Targeted Allocation  Range	Actual Allocation September 30
Security Class		2016		2015
Domestic equities	35%-55%	40.5	%	41.3	%
International equities	10%-20%	15.5	%	14.9	%
Fixed income	5%-30%	11.2	%	11.0	%
Company stock	0%-15%	15.1	%	15.2	%
Other assets	0%-20%	17.7	%	17.6	%

Schedule of Employee Pension Plans Investments at Fair Value

In addition to the assets shown below, the Plan had net accounts receivable of $2.6 million and $2.4 million at September 30, 2016 and 2015 which materially approximates fair value due to the short-term nature of these assets.

	Assets at Fair Value as of September 30, 2016
	Level 1		Level 2		Level 3		Total
	(In thousands)
Investments:
Common stocks	$	157,111	$	—	$	—	$	157,111
Money market funds	—		11,522		—		11,522
Registered investment companies	87,396		—		—		87,396
Common/collective trusts	—		105,124		—		105,124
Government securities:
Mortgage-backed securities	—		15,223		—		15,223
U.S. treasuries	4,704		863		—		5,567
Corporate bonds	—		31,929		—		31,929
Limited partnerships	—		57,438		—		57,438
Total investments at fair value	$	249,211	$	222,099	$	—	$	471,310

	Assets at Fair Value as of September 30, 2015
	Level 1		Level 2		Level 3		Total
	(In thousands)
Investments:
Common stocks	$	159,304	$	—	$	—	$	159,304
Money market funds	—		11,787		—		11,787
Registered investment companies	81,960		—		—		81,960
Common/collective trusts	—		93,081		—		93,081
Government securities:
Mortgage-backed securities	—		14,359		—		14,359
U.S. treasuries	5,279		805		—		6,084
Corporate bonds	—		28,973		—		28,973
Limited partnerships	—		52,996		—		52,996
Total investments at fair value	$	246,543	$	202,001	$	—	$	448,544

Schedule of Expected Benefit Payments

The following benefit payments for our defined benefit plans, which reflect expected future service, as appropriate, are expected to be paid in the following fiscal years:

	Pension Plan		Supplemental Plans
	(In thousands)
2017	$	31,306	$	36,604
2018	32,047		14,289
2019	33,674		7,181
2020	35,232		4,395
2021	37,279		4,306
2022-2026	202,442		60,658

The following benefit payments paid by us, retirees and prescription drug subsidy payments for our postretirement benefit plans, which reflect expected future service, as appropriate, are expected to be paid in the following fiscal years. Company payments for fiscal 2016 include contributions to our postretirement plan trusts.

	Company Payments		Retiree Payments		Subsidy Payments		Total Postretirement Benefits
	(In thousands)
2017	$	15,806	$	3,679	$	—	$	19,485
2018	11,602		3,992		—		15,594
2019	12,165		4,036		—		16,201
2020	13,246		4,756		—		18,002
2021	14,210		5,420		—		19,630
2022-2026	84,642		36,837		—		121,479

Schedule of Postretirement Benefit Plans Investments at Fair Value

	Assets at Fair Value as of September 30, 2016
	Level 1		Level 2		Level 3		Total
	(In thousands)
Investments:
Money market funds	$	—	$	4,470	$	—	$	4,470
Registered investment companies	154,507		—		—		154,507
Total investments at fair value	$	154,507	$	4,470	$	—	$	158,977

	Assets at Fair Value as of September 30, 2015
	Level 1		Level 2		Level 3		Total
	(In thousands)
Investments:
Money market funds	$	—	$	3,486	$	—	$	3,486
Registered investment companies	134,523		—		—		134,523
Total investments at fair value	$	134,523	$	3,486	$	—	$	138,009

Schedule of Assumptions Used [Table Text Block]

The actuarial assumptions used to determine the pension liability for our postretirement plan were determined as of September 30, 2016 and 2015 and the actuarial assumptions used to determine the net periodic pension cost for the postretirement plan were determined as of September 30, 2015, 2014 and 2013. The assumptions are presented in the following table:

	Postretirement Liability				Postretirement Cost
	2016		2015		2016		2015		2014
Discount rate	3.73	%	4.55	%	4.55	%	4.43	%	4.95	%
Expected return on plan assets	4.45	%	4.45	%	4.45	%	4.60	%	4.60	%
Initial trend rate	7.50	%	7.50	%	7.50	%	7.50	%	8.00	%
Ultimate trend rate	5.00	%	5.00	%	5.00	%	5.00	%	5.00	%
Ultimate trend reached in	2022		2021		2021		2020		2020

Additional assumptions are presented in the following table:

	Pension Liability				Pension Cost
	2016		2015		2016		2015		2014
Discount rate	3.73	%	4.55	%	4.55	%	4.43	%	4.95	%
Rate of compensation increase	3.50	%	3.50	%	3.50	%	3.50	%	3.50	%
Expected return on plan assets	7.00	%	7.00	%	7.00	%	7.25	%	7.25	%

The actuarial assumptions used to determine the pension liability for the supplemental plans were determined as of September 30, 2016 and 2015 and the actuarial assumptions used to determine the net periodic pension cost for the supplemental plans were determined as of September 30, 2015, 2014 and 2013. These assumptions are presented in the following table:

	Pension Liability				Pension Cost
	2016		2015		2016		2015		2014
Discount rate	3.73	%	4.55	%	4.55	%	4.43	%	4.95	%
Rate of compensation increase	3.50	%	3.50	%	3.50	%	3.50	%	3.50	%

Changes in Projected Benefit Obligations, Fair Value of Plan Assets, and Funded Status of Plan [Table Text Block]

The following table presents the supplemental plans’ accumulated benefit obligation, projected benefit obligation and funded status as of September 30, 2016 and 2015:

	2016			2015
	(In thousands)
Accumulated benefit obligation	$	137,616		$	118,835
Change in projected benefit obligation:
Benefit obligation at beginning of year	$	122,393		$	113,219
Service cost	2,371			3,971
Interest cost	5,185			4,943
Actuarial loss	17,229			4,811
Benefits paid	(4,604		)	(4,551		)
Benefit obligation at end of year	142,574			122,393
Change in plan assets:
Fair value of plan assets at beginning of year	—			—
Employer contribution	4,604			4,551
Benefits paid	(4,604		)	(4,551		)
Fair value of plan assets at end of year	—			—
Reconciliation:
Funded status	(142,574		)	(122,393		)
Unrecognized prior service cost	—			—
Unrecognized net loss	—			—
Accrued pension cost	$	(142,574	)	$	(122,393	)

The following table presents the Plan’s accumulated benefit obligation, projected benefit obligation and funded status as of September 30, 2016 and 2015:

	2016			2015
	(In thousands)
Accumulated benefit obligation	$	516,924		$	485,921
Change in projected benefit obligation:
Benefit obligation at beginning of year	$	508,599		$	493,594
Service cost	16,419			16,231
Interest cost	23,193			21,850
Actuarial loss	41,847			7,420
Benefits paid(1)	(44,578		)	(30,496		)
Benefit obligation at end of year	545,480			508,599
Change in plan assets:
Fair value of plan assets at beginning of year	450,932			434,767
Actual return on plan assets	52,596			8,661
Employer contributions	15,000			38,000
Benefits paid(1)	(44,578		)	(30,496		)
Fair value of plan assets at end of year	473,950			450,932
Reconciliation:
Funded status	(71,530		)	(57,667		)
Unrecognized prior service cost	—			—
Unrecognized net loss	—			—
Accrued pension cost	$	(71,530	)	$	(57,667	)

The following table presents the postretirement plan’s benefit obligation and funded status as of September 30, 2016 and 2015:

	2016			2015
	(In thousands)
Change in benefit obligation:
Benefit obligation at beginning of year	$	267,179		$	315,118
Service cost	10,823			15,583
Interest cost	12,424			14,385
Plan participants’ contributions	4,289			4,563
Actuarial gain	(1,052		)	(69,962		)
Benefits paid	(14,441		)	(12,508		)
Benefit obligation at end of year	279,222			267,179
Change in plan assets:
Fair value of plan assets at beginning of year	138,009			134,821
Actual return on plan assets	14,528			(8,851		)
Employer contributions	16,592			19,984
Plan participants’ contributions	4,289			4,563
Benefits paid	(14,441		)	(12,508		)
Fair value of plan assets at end of year	158,977			138,009
Reconciliation:
Funded status	(120,245		)	(129,170		)
Unrecognized transition obligation	—			—
Unrecognized prior service cost	—			—
Unrecognized net loss	—			—
Accrued postretirement cost	$	(120,245	)	$	(129,170	)

Schedule of Net Benefit Costs [Table Text Block]

Net periodic pension cost for the Plan for fiscal 2016, 2015 and 2014 is recorded as operating expense and included the following components:

	Fiscal Year Ended September 30
	2016			2015			2014
	(In thousands)
Components of net periodic pension cost:
Service cost	$	16,419		$	16,231		$	15,345
Interest cost	23,193			21,850			22,330
Expected return on assets	(27,522		)	(25,744		)	(23,601		)
Amortization of prior service credit	(226		)	(192		)	(136		)
Recognized actuarial loss	10,693			13,322			13,777
Net periodic pension cost	$	22,557		$	25,467		$	27,715

Net periodic postretirement cost for fiscal 2016, 2015 and 2014 is recorded as operating expense and included the components presented below.

	Fiscal Year Ended September 30
	2016			2015			2014
	(In thousands)
Components of net periodic postretirement cost:
Service cost	$	10,823		$	15,583		$	16,784
Interest cost	12,424			14,385			15,951
Expected return on assets	(6,264		)	(6,431		)	(5,167		)
Amortization of transition obligation	82			272			274
Amortization of prior service credit	(1,644		)	(1,644		)	(1,450		)
Recognized actuarial (gain) loss	(2,167		)	—			631
Net periodic postretirement cost	$	13,254		$	22,165		$	27,023

Net periodic pension cost for the supplemental plans for fiscal 2016, 2015 and 2014 is recorded as operating expense and included the following components:

	Fiscal Year Ended September 30
	2016		2015		2014
	(In thousands)
Components of net periodic pension cost:
Service cost	$	2,371	$	3,971	$	3,607
Interest cost	5,185		4,943		4,966
Amortization of transition asset	—		—		—
Amortization of prior service cost	—		—		—
Recognized actuarial loss	2,586		2,343		1,948
Settlements	—		—		4,539
Net periodic pension cost	$	10,142	$	11,257	$	15,060

Schedule of Effect of One-Percentage-Point Change in Assumed Health Care Cost Trend Rates [Table Text Block]

Assumed health care cost trend rates have a significant effect on the amounts reported for the plan. A one-percentage point change in assumed health care cost trend rates would have the following effects on the latest actuarial calculations:

	One-Percentage Point Increase		One-Percentage Point Decrease
	(In thousands)
Effect on total service and interest cost components	$	4,539	$	(3,596	)
Effect on postretirement benefit obligation	$	42,079	$	(34,531	)