Long-Term Debt (Detail) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016	Jun. 30, 2016
Debt Instrument [Line Items]
Total debt	$ 1,781,981	$ 1,686,189	$ 1,779,217
Less: Current maturities of long-term debt and short-term facilities	(140,037)	(180,036)	(238,155)
Long-term debt	1,641,944	1,506,153	1,541,062
Revolving Facility, Due 2021
Debt Instrument [Line Items]
Total debt		160,000
6.6% Senior Notes, Due 2018
Debt Instrument [Line Items]
Total debt	299,676	299,483	299,294
7% Debentures, Due 2025
Debt Instrument [Line Items]
Total debt	124,134	124,090	124,046
6.25% Senior Notes, Due 2037
Debt Instrument [Line Items]
Total debt	228,003	227,975	227,947
4.25% Senior Notes, Due 2024
Debt Instrument [Line Items]
Total debt	395,532	395,252	394,977
3.45% Senior Notes, Due 2027
Debt Instrument [Line Items]
Total debt	296,456
Floating Rate Notes, Due 2017
Debt Instrument [Line Items]
Total debt		299,033	298,793
Floating Rate Notes, Due 2020
Debt Instrument [Line Items]
Total debt	297,847
Term Loan Facility, Due 2018
Debt Instrument [Line Items]
Total debt			213,571
Trade Receivable Facility
Debt Instrument [Line Items]
Total debt	140,000	180,000	220,000
Other Notes
Debt Instrument [Line Items]
Total debt	$ 333	$ 356	$ 589