Retirement and Post-Retirement Employee Benefit Plans Fair Value Disclosures (Details) - USD ($) $ in Thousands		Sep. 30, 2015	Sep. 30, 2014
Schedule of Total Investments at Fair Value [Line Items]
Available-for-sale Securities		$ 74,200	$ 79,613
Fair Value Inputs Level 1 [Member]
Schedule of Total Investments at Fair Value [Line Items]
Available-for-sale Securities		40,619	44,014
Fair Value Inputs Level 2 [Member]
Schedule of Total Investments at Fair Value [Line Items]
Available-for-sale Securities	[1]	33,581	35,599
Fair Value Inputs Level 3 [Member]
Schedule of Total Investments at Fair Value [Line Items]
Available-for-sale Securities		0	0
Pension Plans, Defined Benefit [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		448,544	432,109
Fair value of accounts receivable		2,400	2,700
Pension Plans, Defined Benefit [Member] | Equity Securities [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		159,304	155,107
Pension Plans, Defined Benefit [Member] | Money Market Funds [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		11,787	11,226
Pension Plans, Defined Benefit [Member] | Registered Investment Companies, Domestic [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		33,312	33,266
Pension Plans, Defined Benefit [Member] | Registered Investment Companies, International [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		48,648	48,134
Pension Plans, Defined Benefit [Member] | Common Collective Trusts [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		93,081	91,792
Pension Plans, Defined Benefit [Member] | Mortgage-backed securities [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		14,359	12,520
Pension Plans, Defined Benefit [Member] | U.S. Treasuries [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		6,084	3,679
Pension Plans, Defined Benefit [Member] | Corporate Debt Securities [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		28,973	25,734
Pension Plans, Defined Benefit [Member] | Limited Partnership Interest [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		52,996	50,496
Pension Plans, Defined Benefit [Member] | Real Estate Investment [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure			155
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 1 [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		246,543	239,624
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 1 [Member] | Equity Securities [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		159,304	155,107
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 1 [Member] | Money Market Funds [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		0	0
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 1 [Member] | Registered Investment Companies, Domestic [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		33,312	33,266
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 1 [Member] | Registered Investment Companies, International [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		48,648	48,134
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 1 [Member] | Common Collective Trusts [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		0	0
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 1 [Member] | Mortgage-backed securities [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		0	0
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 1 [Member] | U.S. Treasuries [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		5,279	3,117
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 1 [Member] | Corporate Debt Securities [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		0	0
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 1 [Member] | Limited Partnership Interest [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		0	0
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 1 [Member] | Real Estate Investment [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure			0
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 2 [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		202,001	192,330
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 2 [Member] | Equity Securities [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		0	0
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 2 [Member] | Money Market Funds [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		11,787	11,226
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 2 [Member] | Registered Investment Companies, Domestic [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		0	0
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 2 [Member] | Registered Investment Companies, International [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		0	0
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 2 [Member] | Common Collective Trusts [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		93,081	91,792
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 2 [Member] | Mortgage-backed securities [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		14,359	12,520
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 2 [Member] | U.S. Treasuries [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		805	562
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 2 [Member] | Corporate Debt Securities [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		28,973	25,734
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 2 [Member] | Limited Partnership Interest [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		52,996	50,496
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 2 [Member] | Real Estate Investment [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure			0
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 3 [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		0	155
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 3 [Member] | Equity Securities [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		0	0
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 3 [Member] | Money Market Funds [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		0	0
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 3 [Member] | Registered Investment Companies, Domestic [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		0	0
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 3 [Member] | Registered Investment Companies, International [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		0	0
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 3 [Member] | Common Collective Trusts [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		0	0
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 3 [Member] | Mortgage-backed securities [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		0	0
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 3 [Member] | U.S. Treasuries [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		0	0
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 3 [Member] | Corporate Debt Securities [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		0	0
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 3 [Member] | Limited Partnership Interest [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		0	0
Pension Plans, Defined Benefit [Member] | Fair Value Inputs Level 3 [Member] | Real Estate Investment [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure			155
Supplemental Employee Retirement Plan [Member]
Schedule of Total Investments at Fair Value [Line Items]
Available-for-sale Securities		41,700	46,200
Other Postretirement Benefit Plans, Defined Benefit [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		138,009	134,821
Other Postretirement Benefit Plans, Defined Benefit [Member] | Money Market Funds [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		3,486	434
Other Postretirement Benefit Plans, Defined Benefit [Member] | Registered Investment Companies, Domestic [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		123,921	124,006
Other Postretirement Benefit Plans, Defined Benefit [Member] | Registered Investment Companies, International [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		10,602	10,381
Other Postretirement Benefit Plans, Defined Benefit [Member] | Fair Value Inputs Level 1 [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		134,523	134,387
Other Postretirement Benefit Plans, Defined Benefit [Member] | Fair Value Inputs Level 1 [Member] | Money Market Funds [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		0	0
Other Postretirement Benefit Plans, Defined Benefit [Member] | Fair Value Inputs Level 1 [Member] | Registered Investment Companies, Domestic [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		123,921	124,006
Other Postretirement Benefit Plans, Defined Benefit [Member] | Fair Value Inputs Level 1 [Member] | Registered Investment Companies, International [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		10,602	10,381
Other Postretirement Benefit Plans, Defined Benefit [Member] | Fair Value Inputs Level 2 [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		3,486	434
Other Postretirement Benefit Plans, Defined Benefit [Member] | Fair Value Inputs Level 2 [Member] | Money Market Funds [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		3,486	434
Other Postretirement Benefit Plans, Defined Benefit [Member] | Fair Value Inputs Level 2 [Member] | Registered Investment Companies, Domestic [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		0	0
Other Postretirement Benefit Plans, Defined Benefit [Member] | Fair Value Inputs Level 2 [Member] | Registered Investment Companies, International [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		0	0
Other Postretirement Benefit Plans, Defined Benefit [Member] | Fair Value Inputs Level 3 [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		0	0
Other Postretirement Benefit Plans, Defined Benefit [Member] | Fair Value Inputs Level 3 [Member] | Money Market Funds [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		0	0
Other Postretirement Benefit Plans, Defined Benefit [Member] | Fair Value Inputs Level 3 [Member] | Registered Investment Companies, Domestic [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		0	0
Other Postretirement Benefit Plans, Defined Benefit [Member] | Fair Value Inputs Level 3 [Member] | Registered Investment Companies, International [Member]
Schedule of Total Investments at Fair Value [Line Items]
Investments, Fair Value Disclosure		$ 0	$ 0

[1] Our Level 2 measurements consist of over-the-counter options and swaps, which are valued using a market-based approach in which observable market prices are adjusted for criteria specific to each instrument, such as the strike price, notional amount or basis differences, municipal and corporate bonds, which are valued based on the most recent available quoted market prices and money market funds which are valued at cost.