Changes In Equity And Comprehensive Income (Summary Of Changes In Equity) (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Changes In Equity And Comprehensive Income [Line Items]
Balance, beginning of period			$ 822,056
Net income	57,307	52,406	171,850	151,321
Other comprehensive income (loss)	2,279	(51,949)	10,784	(7,712)
Comprehensive income	59,586	457	182,634	143,609
Balance, end of period	932,752		932,752
Total Shareholders' Equity
Changes In Equity And Comprehensive Income [Line Items]
Balance, beginning of period			813,553	984,944
Dividends			(45,998)	(41,957)
Reacquisition on open market			(49,991)	(49,999)
Exercise of stock options, net of shares reacquired			7,958	19,907
Stock compensation expense			12,860	11,132
Excess tax benefit from stock based compensation			3,233	5,706
Net income			171,349	151,444
Other comprehensive income (loss)			11,201	(7,840)
Comprehensive income			182,550	143,604
Balance, end of period	924,165	1,073,337	924,165	1,073,337
Noncontrolling Interest
Changes In Equity And Comprehensive Income [Line Items]
Balance, beginning of period			8,503	8,086
Net income			501	(123)
Other comprehensive income (loss)			(417)	128
Comprehensive income			84	5
Balance, end of period	8,587	8,091	8,587	8,091
Total Equity
Changes In Equity And Comprehensive Income [Line Items]
Balance, beginning of period			822,056	993,030
Dividends			(45,998)	(41,957)
Reacquisition on open market			(49,991)	(49,999)
Exercise of stock options, net of shares reacquired			7,958	19,907
Stock compensation expense			12,860	11,132
Excess tax benefit from stock based compensation			3,233	5,706
Net income			171,850	151,321
Other comprehensive income (loss)			10,784	(7,712)
Comprehensive income			182,634	143,609
Balance, end of period	$ 932,752	$ 1,081,428	$ 932,752	$ 1,081,428