Income Tax Effects Allocated to and Cumulative Balance of Accumulated Other Comprehensive Income (loss) (Detail) $ in Thousands	6 Months Ended
	Jun. 30, 2016 USD ($)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	$ 1,843,018
Ending Balance	1,985,428
Foreign currency translation adjustments and transfers from noncontrolling interests
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(35,013)
Pretax Amount	(16,879)
Tax Effect	(3,284)
Net-of-Tax Amount	(13,595)
Ending Balance	(48,609)
Unrealized gain on available-for-sale securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	2,503
Pretax Amount	1,004
Tax Effect	361
Net-of-Tax Amount	643
Ending Balance	3,146
Change in AOCI related to postretirement healthcare plans
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(1,034)
Pretax Amount	(1,224)
Tax Effect	(443)
Net-of-Tax Amount	(781)
Ending Balance	(1,814)
Accumulated Other Comprehensive Income (Loss) (OCI)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(33,544)
Pretax Amount	(17,099)
Tax Effect	(3,366)
Net-of-Tax Amount	(13,733)
Ending Balance	$ (47,277)