Long-Term Debt And Notes Payable (Components Of Debt) (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Debt Instrument [Line Items]
6.55% notes due 2036	$ 399,003	$ 398,914
Short-term borrowings	1,102	1,112
5.50% Notes Due 2013
Debt Instrument [Line Items]
6.55% notes due 2036	199,825	199,753
6.55% Notes Due 2036
Debt Instrument [Line Items]
6.55% notes due 2036	$ 199,178	$ 199,161