Benefit Plans - Fair Value Measurements of U.S. Plan Assets (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012		Sep. 30, 2011		Sep. 30, 2010
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 83,160		$ 89,291		$ 71,997
U.S. plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,106,892		933,278
U.S. plans [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	746,146		499,661
U.S. plans [Member] | Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	360,746		433,617
U.S. plans [Member] | Mortgage and asset-backed securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	137,064	[1]	165,042	[1]
U.S. plans [Member] | Mortgage and asset-backed securities [Member] | Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	137,064	[1]	165,042	[1]
U.S. plans [Member] | Corporate bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	106,981	[2]	111,954	[2]
U.S. plans [Member] | Corporate bonds [Member] | Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	106,981	[2]	111,954	[2]
U.S. plans [Member] | Government and agency-U.S. [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	74,641	[3]	41,885	[3]
U.S. plans [Member] | Government and agency-U.S. [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	57,401	[3]	26,577	[3]
U.S. plans [Member] | Government and agency-U.S. [Member] | Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	17,240	[3]	15,308	[3]
U.S. plans [Member] | Government and agency-Foreign [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	5,696	[4]	6,836	[4]
U.S. plans [Member] | Government and agency-Foreign [Member] | Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	5,696	[4]	6,836	[4]
U.S. plans [Member] | Other [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	8,964	[5]	8,277	[5]
U.S. plans [Member] | Other [Member] | Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	8,964	[5]	8,277	[5]
U.S. plans [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	724,447	[6]	562,047	[6]
U.S. plans [Member] | Equity Securities [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	639,646	[6]	435,847	[6]
U.S. plans [Member] | Equity Securities [Member] | Significant Other Observable Inputs (Level 2) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	84,801	[6]	126,200	[6]
U.S. plans [Member] | Cash and cash equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	49,099	[7]	37,237	[7]
U.S. plans [Member] | Cash and cash equivalents [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 49,099	[7]	$ 37,237	[7]

[1] Values are based upon a combination of observable prices, independent pricing services and relevant broker quotes.

[2] Values are based upon comparable securities with similar yields and credit ratings.

[3] Values of instruments classified as Level 1 are based on the closing price reported on the major market on which the investments are traded. Values of instruments classified as Level 2 are based upon quoted market prices from observable pricing sources.

[4] Values are based upon quoted market prices from observable pricing sources.

[5] Classification contains various immaterial investments and valuation varies by investment type. Values are primarily based upon quoted market prices from observable pricing sources.

[6] Values of instruments classified as Level 1 are based on the closing price reported on the major market on which the investments are traded. Values of instruments classified as Level 2 are based on the net asset value provided by the fund administrator, which is based on the value of the underlying assets owned by the fund, less its liabilities and then divided by the number of fund units outstanding.

[7] Values are based upon quoted market prices or broker/dealer quotations.