Supplementary Balance Sheet Information - Income Tax Effects Allocated to and Cumulative Balance of Accumulated Other Comprehensive Income (loss) (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2016 USD ($)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	$ 1,843,018
Ending Balance	2,065,669
Foreign currency translation adjustments and transfers from noncontrolling interests
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(35,013)
Pretax Amount	(20,298)
Tax Effect	(4,035)
Net-of-Tax Amount	(16,263)
Ending Balance	(51,276)
Unrealized gain on available-for-sale securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	2,503
Pretax Amount	2,936
Tax Effect	1,128
Net-of-Tax Amount	1,808
Ending Balance	4,311
Change in AOCI related to postretirement healthcare plans
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(1,034)
Pretax Amount	582
Tax Effect	209
Net-of-Tax Amount	373
Ending Balance	(661)
Accumulated Other Comprehensive Income (Loss) (OCI)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(33,544)
Pretax Amount	(16,780)
Tax Effect	(2,698)
Net-of-Tax Amount	(14,082)
Ending Balance	$ (47,626)