Common Stock and Treasury Stock - Additional Information (Detail) - USD ($)	12 Months Ended			48 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2015	Feb. 28, 2014	Jul. 31, 2013	Sep. 13, 2012	Feb. 29, 2012	Dec. 31, 2011
Maximum stock authorized to purchase under stock repurchase program								$ 262,100,000	$ 210,000,000
Increase in maximum stock authorized to purchase under stock repurchase program					$ 100,000,000	$ 100,000,000		$ 52,100,000
Repurchase of common stock, shares	0	3,578,427	4,970,424	37,108,467
Repurchase of common stock, value		$ 70,000,000	$ 80,912,000	$ 395,800,000
Number shares issued pursuant to stock option exercises	1,144,273	2,036,558	2,478,183
Long-term incentive program performance share awards
Stock issued during the period performance share award	548,671	635,643	982,728
Restricted share awards (RSAs) [Member]
Stock issued during period, performance based restricted share awards	125,026	106,275	25,989
Performance-Based Restricted Share Awards
Stock issued during period, performance based restricted share awards	978,365
Stock Options [Member]
Number shares issued pursuant to stock option exercises	1,146,199	2,037,467	2,493,684
Maximum
Maximum stock authorized to purchase under stock repurchase program							$ 113,000,000
Stock authorized to purchase under stock repurchase program, shares							7,500,000
Remaining value of shares authorized for purchase under the stock repurchase program	$ 138,300,000			$ 138,300,000