Long-Term Debt And Notes Payable (Components Of Debt) (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013
Debt Instrument [Line Items]
Net decrease in short-term debt	$ 18,000	$ 0
6.55% notes due 2036	749,181		749,170
Short-term borrowings	143,804		125,826
2.75% Notes Due 2013
Debt Instrument [Line Items]
6.55% notes due 2036	249,967		249,965
4.45% Notes Due 2018
Debt Instrument [Line Items]
6.55% notes due 2036	299,977		299,976
6.55% Notes Due 2023
Debt Instrument [Line Items]
6.55% notes due 2036	199,237		199,229
Six Point Five Five Percent Notes Due 2036 [Member]
Debt Instrument [Line Items]
6.55% notes due 2036	$ 749,181		$ 749,170