Changes In Equity And Comprehensive Income (Summary Of Changes In Equity) (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period	$ 1,150.8	$ 1,070.6
Dividends	19.2	19.1
Reacquisition on open market	0.0	25.0
Exercise of stock options, net of shares reacquired	(1.4)	6.7
Stock compensation expense	6.1	5.8
Excess tax benefit from stock based compensation	(0.3)	0.9
Net income	55.2	51.3
Other comprehensive income (loss)	33.7	(68.9)
Comprehensive income	88.9	(17.6)
Balance, end of period	1,224.9	1,022.3
Parent [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period	1,139.4	1,059.8
Dividends	(19.2)	(19.1)
Reacquisition on open market	0.0	(25.0)
Exercise of stock options, net of shares reacquired	(1.4)	6.7
Stock compensation expense	6.1	5.8
Excess tax benefit from stock based compensation	(0.3)	0.9
Net income	55.0	51.1
Other comprehensive income (loss)	33.6	(68.7)
Comprehensive income	88.6	(17.7)
Balance, end of period	1,213.2	1,011.4
Noncontrolling Interest
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance, beginning of period	11.4	10.8
Net income	0.2	0.3
Other comprehensive income (loss)	0.1	(0.2)
Comprehensive income		0.1
Balance, end of period	$ 11.7	$ 10.9