Fair Value of Plan Assets by Asset Category (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	$ 704,779	$ 754,979
Equity Securities \| United States
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	336,297	358,067
Equity Securities \| International
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	70,552	74,999
Debt securities
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	294,125	317,562
Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	$ 3,805	$ 4,351

Assets, usually stocks, bonds, and other investments, that have been segregated and restricted (usually in a trust) to provide benefits, at their fair value as of the measurement date. Plan assets include amounts contributed by the employer (and by employees for a contributory plan) and amounts earned from investing the contributions, less benefits paid. If a plan has liabilities other than for benefits, those non-benefit obligations may be considered as reductions of plan assets.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 30
-Section 35
-Paragraph 50
-URI http://asc.fasb.org/extlink&oid=49178875&loc=d3e12355-114930

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e1928-114920

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant