Accumulated Other Comprehensive Income - Schedule of Changes in Accumulated Other Comprehensive Income (Losses) (Detail) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	$ (148,953)	$ (197,413)	$ (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)	(29,855)	24,318	(20,325)	30,128
Amounts reclassified from accumulated other comprehensive income (net of tax)	4,202	2,014	8,692	3,397
Net current period other comprehensive income (loss)	(25,653)	26,332	(11,633)	33,525
Ending Balance	(174,606)	(171,081)	(174,606)	(171,081)
Currency Translation Adjustments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(29,092)	(94,383)	(41,839)	(100,448)
Balance as adjusted at January 1, 2018			(41,839)
Other comprehensive income (loss) before reclassifications (net of tax)	(33,223)	27,504	(20,476)	33,569
Net current period other comprehensive income (loss)	(33,223)	27,504	(20,476)	33,569
Ending Balance	(62,315)	(66,879)	(62,315)	(66,879)
Unrealized Gain (Loss) on Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(5,894)	554	(4,092)	1,500
Balance as adjusted at January 1, 2018			(4,092)
Other comprehensive income (loss) before reclassifications (net of tax)	3,368	(3,080)	151	(3,335)
Amounts reclassified from accumulated other comprehensive income (net of tax)	1,181	(571)	2,596	(1,262)
Net current period other comprehensive income (loss)	4,549	(3,651)	2,747	(4,597)
Ending Balance	(1,345)	(3,097)	(1,345)	(3,097)
Change in Pensions [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(118,428)	(108,466)	(98,295)	(110,656)
Amount reclassified for adoption of ASU No. 2018-02			(23,297)
Balance as adjusted at January 1, 2018			(121,592)
Amounts reclassified from accumulated other comprehensive income (net of tax)	3,261	2,642	6,425	4,832
Net current period other comprehensive income (loss)	3,261	2,642	6,425	4,832
Ending Balance	(115,167)	(105,824)	(115,167)	(105,824)
Change in Other Postretirement Defined Benefit Plans [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	4,461	4,882	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)		(106)		(106)
Amounts reclassified from accumulated other comprehensive income (net of tax)	(240)	(57)	(329)	(173)
Net current period other comprehensive income (loss)	(240)	(163)	(329)	(279)
Ending Balance	$ 4,221	$ 4,719	$ 4,221	$ 4,719

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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