Long-Term Debt (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016
Debt Instrument [Line Items]
Total debt	$ 1,722,540	$ 1,686,189	$ 1,764,835
Less: Current maturities of long-term debt and short-term facilities	(80,038)	(180,036)	(228,025)
Long-term debt	1,642,502	1,506,153	1,536,810
Revolving Facility, Due 2021
Debt Instrument [Line Items]
Total debt		160,000
6.60% Senior Notes, Due 2018
Debt Instrument [Line Items]
Total debt	299,774	299,483	299,388
7% Debentures, Due 2025
Debt Instrument [Line Items]
Total debt	124,157	124,090	124,068
6.25% Senior Notes, Due 2037
Debt Instrument [Line Items]
Total debt	228,018	227,975	227,961
4.25% Senior Notes, Due 2024
Debt Instrument [Line Items]
Total debt	395,673	395,252	395,115
3.450% Senior Notes, Due 2027
Debt Instrument [Line Items]
Total debt	296,551
Floating Rate Notes, Due 2017
Debt Instrument [Line Items]
Total debt		299,033	298,750
Floating Rate Notes, Due 2020
Debt Instrument [Line Items]
Total debt	298,046
Term Loan Facility, Due 2018
Debt Instrument [Line Items]
Total debt			209,096
Trade Receivable Facility
Debt Instrument [Line Items]
Total debt	80,000	180,000	210,000
Other Notes
Debt Instrument [Line Items]
Total debt	$ 321	$ 356	$ 457