Changes In Equity And Comprehensive Income (Summary Of Changes In Equity) (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period	$ 927,376	$ 822,056
Dividends	(16,144)	(15,090)
Reacquisition on open market	0	0
Exercise of stock options, net of shares reacquired	13,609	7,323
Stock compensation expense	5,379	4,007
Excess tax benefit from stock based compensation	2,928	2,947
Net income	57,942	51,796
Other comprehensive income (loss)	(17,797)	22,817
Comprehensive income	40,145	74,613
Balance, end of period	973,293	895,856
Parent [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period	918,383	813,553
Dividends	(16,144)	(15,090)
Reacquisition on open market	0	0
Exercise of stock options, net of shares reacquired	13,609	7,323
Stock compensation expense	5,379	4,007
Excess tax benefit from stock based compensation	2,928	2,947
Net income	57,791	51,662
Other comprehensive income (loss)	(17,807)	22,791
Comprehensive income	39,984	74,453
Balance, end of period	964,139	887,193
Noncontrolling Interest
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period	8,993	8,503
Net income	151	134
Other comprehensive income (loss)	10	26
Comprehensive income	161	160
Balance, end of period	$ 9,154	$ 8,663