Capital Stock - Additional Information (Detail) (USD $)	0 Months Ended	1 Months Ended				12 Months Ended			1 Months Ended
	Nov. 23, 2010	Nov. 19, 2012	Nov. 19, 2011	Nov. 23, 2010	Nov. 08, 2010	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Feb. 08, 2013 Subsequent Event	Feb. 08, 2013 Subsequent Event Co- Chairman Of Board Of Directors
Stockholders Equity Note [Line Items]
Common stock, shares authorized						200,000,000	200,000,000
Common stock, par value						$ 0.01	$ 0.01
Preferred stock, shares authorized						10,000,000
Preferred stock, par value						$ 0.01
Common stock authorized for repurchase			$ 100,000,000				$ 300,000,000
Repurchases of common stock						805,346	441,416
Common stock repurchased, purchase price per share						$ 42.35	$ 35.79
Common stock repurchased, total purchase price						34,109,000	15,797,000	247,825,000
Common stock repurchase, remaining authorized amount						350,100,000
Treasury shares issued						132,846	374,071	163,428
Average cost for restricted stock units						$ 6.63	$ 6.63	$ 6.63
Shares repurchased to satisfy employee withholding tax requirements resulting from certain restricted stock units becoming vested						43,874	142,080	51,038
Common stock repurchased, average cost						$ 42.64	$ 36.58	$ 28.82
Treasury stock, shares						18,352,281	17,635,907
Dollar amount of common stock intended to purchase through modified dutch auction tender offer		250,000,000
Common stock purchased through modified dutch auction tender offer - in shares					5,035,971				5,524,861	515,806
Common stock purchased through modified dutch auction tender offer - price per share					$ 34.75				$ 45.25	$ 45.25
Common stock purchased through modified dutch auction tender offer - total purchase price in dollars					175,000,000				250,000,000	23,300,000
Common stock purchased from stockholders under stock purchase agreement - in shares				2,071,509
Common stock purchased from stockholders under stock purchase agreement - price per share				$ 34.75
Common stock purchased from stockholders under stock purchase agreement - total purchase price in dollars				72,000,000
Common stock purchased from stockholders under stock purchase agreement and through tender offer - in shares	7,107,480
Common stock purchased from stockholders under stock purchase agreement and through tender offer- price per share	$ 34.75
Common stock purchased from stockholders under stock purchase agreement and through tender offer - total purchase price in dollars	$ 247,000,000