Shareholders' Equity (Narrative) (Detail) (USD $) In Millions, except Share data, unless otherwise specified	1 Months Ended	3 Months Ended	9 Months Ended
	Oct. 26, 2011	Sep. 30, 2012	Sep. 30, 2012	Jun. 30, 2012
Preferred stock, shares outstanding		0	0	0
Preferred stock, shares authorized		5,000,000	5,000,000	5,000,000
Preferred stock, par value		$ 0.01	$ 0.01	$ 0.01
Common stock, shares authorized		200,000,000	200,000,000	200,000,000
Common stock, par value		$ 0.01	$ 0.01	$ 0.01
Common stock, shares issued		96,789,278	96,789,278	96,132,542
Treasury stock, shares		28,976,192	28,976,192	28,846,226
Common stock, shares outstanding		67,813,086	67,813,086	67,286,316
Board of Directors authorized the repurchase of common stock	$ 200
Repurchased shares under the buyback program		129,966	3,376,375
Cost of repurchased shares under buyback program		4.8	128.8
Expiry date of share buyback program		Oct. 25, 2012	Oct. 25, 2012
Investments included in other current assets		$ 1.9	$ 1.9	$ 1.8