Accumulated Other Comprehensive Income - Schedule of Changes in Accumulated Other Comprehensive Income (Losses) (Detail) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	$ (174,606)	$ (171,081)	$ (140,675)	$ (204,606)
Amount reclassified for adoption of ASU No. 2018-02			(22,298)
Balance as adjusted at January 1, 2018			(162,973)
Other comprehensive income (loss) before reclassifications (net of tax)	15,090	15,026	(5,235)	45,261
Amounts reclassified from accumulated other comprehensive income (net of tax)	4,881	2,304	13,573	5,594
Net current period other comprehensive income (loss)	19,971	17,330	8,338	50,855
Ending Balance	(154,635)	(153,751)	(154,635)	(153,751)
Currency Translation Adjustments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(62,315)	(66,879)	(41,839)	(100,448)
Balance as adjusted at January 1, 2018			(41,839)
Other comprehensive income (loss) before reclassifications (net of tax)	(3,217)	16,559	(23,693)	50,128
Net current period other comprehensive income (loss)	(3,217)	16,559	(23,693)	50,128
Ending Balance	(65,532)	(50,320)	(65,532)	(50,320)
Unrealized Gain (Loss) on Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(1,345)	(3,097)	(4,092)	1,500
Balance as adjusted at January 1, 2018			(4,092)
Other comprehensive income (loss) before reclassifications (net of tax)	627	(1,533)	778	(4,868)
Amounts reclassified from accumulated other comprehensive income (net of tax)	989	19	3,585	(1,243)
Net current period other comprehensive income (loss)	1,616	(1,514)	4,363	(6,111)
Ending Balance	271	(4,611)	271	(4,611)
Change in Pensions [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(115,167)	(105,824)	(98,295)	(110,656)
Amount reclassified for adoption of ASU No. 2018-02			(23,297)
Balance as adjusted at January 1, 2018			(121,592)
Other comprehensive income (loss) before reclassifications (net of tax)	12,981		12,981
Amounts reclassified from accumulated other comprehensive income (net of tax)	4,053	2,424	10,478	7,256
Net current period other comprehensive income (loss)	17,034	2,424	23,459	7,256
Ending Balance	(98,133)	(103,400)	(98,133)	(103,400)
Change in Other Postretirement Defined Benefit Plans [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	4,221	4,719	3,551	4,998
Amount reclassified for adoption of ASU No. 2018-02			999
Balance as adjusted at January 1, 2018			4,550
Other comprehensive income (loss) before reclassifications (net of tax)	4,699		4,699	1
Amounts reclassified from accumulated other comprehensive income (net of tax)	(161)	(139)	(490)	(419)
Net current period other comprehensive income (loss)	4,538	(139)	4,209	(418)
Ending Balance	$ 8,759	$ 4,580	$ 8,759	$ 4,580

Accumulated other comprehensive income loss net of tax adjusted balance.

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Accumulated change in equity from transactions and other events and circumstances from non-owner sources, net of tax effect, at period end. Excludes Net Income (Loss), and accumulated changes in equity from transactions resulting from investments by owners and distributions to owners. Includes foreign currency translation items, certain pension adjustments, unrealized gains and losses on certain investments in debt and equity securities, other than temporary impairment (OTTI) losses related to factors other than credit losses on available-for-sale and held-to-maturity debt securities that an entity does not intend to sell and it is not more likely than not that the entity will be required to sell before recovery of the amortized cost basis, as well as changes in the fair value of derivatives related to the effective portion of a designated cash flow hedge.

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Amount after tax of increase (decrease) to equity or (increase) decrease to net assets, resulting from the cumulative effect adjustment of a new accounting principle applied in the period of adoption.

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Amount after tax, before reclassification adjustments of other comprehensive income (loss).

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