Summary of Significant Accounting Policies - Changes in Accumulated Other Comprehensive Loss (Detail) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017
Changes in Accumulated Other Comprehensive Loss by Component
Beginning balance	$ 3,412,152
Other comprehensive income (loss) before reclassifications, net of tax	(292,329)	$ 137,253
Amounts reclassified from accumulated other comprehensive loss, net of tax	29,843	23,176
Net current period other comprehensive (loss) income	(262,486)	160,429
Ending balance	3,450,451	3,412,152
Cash Flow and Net Investment Hedges [Member]
Changes in Accumulated Other Comprehensive Loss by Component
Beginning balance	(17,388)	0
Other comprehensive income (loss) before reclassifications, net of tax	26,563	(17,388)
Amounts reclassified from accumulated other comprehensive loss, net of tax	1,551	0
Net current period other comprehensive (loss) income	28,114	(17,388)
Ending balance	10,726	(17,388)
Foreign Currency Translation [Member]
Changes in Accumulated Other Comprehensive Loss by Component
Beginning balance	(266,247)	(403,941)
Other comprehensive income (loss) before reclassifications, net of tax	(233,235)	137,694
Amounts reclassified from accumulated other comprehensive loss, net of tax	0	0
Net current period other comprehensive (loss) income	(233,235)	137,694
Ending balance	(499,482)	(266,247)
Accumulated Other Comprehensive Loss [Member]
Changes in Accumulated Other Comprehensive Loss by Component
Beginning balance	(852,592)	(1,013,021)
Ending balance	(1,115,078)	(852,592)
Pension Plan [Member] \| Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Changes in Accumulated Other Comprehensive Loss by Component
Beginning balance	(567,443)	(607,468)
Other comprehensive income (loss) before reclassifications, net of tax	(85,677)	16,640
Amounts reclassified from accumulated other comprehensive loss, net of tax	28,581	23,385
Net current period other comprehensive (loss) income	(57,096)	40,025
Ending balance	(624,539)	(567,443)
Other Postretirement Benefits Plan [Member] \| Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Changes in Accumulated Other Comprehensive Loss by Component
Beginning balance	(1,514)	(1,612)
Other comprehensive income (loss) before reclassifications, net of tax	20	307
Amounts reclassified from accumulated other comprehensive loss, net of tax	(289)	(209)
Net current period other comprehensive (loss) income	(269)	98
Ending balance	$ (1,783)	$ (1,514)

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

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