Share-Based Compensation - Schedule of Stock Options (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Options outstanding - Beginning Balance, Shares	1,371,850	1,715,380	2,563,708
Granted, Shares	585,189
Exercised, Shares	(1,065,920)	(217,634)	(847,528)
Cancelled, Shares	(78,959)	(125,896)	(800)
Options outstanding - Ending Balance, Shares	812,160	1,371,850	1,715,380
Number of options exercisable, Shares	305,930	1,371,850	1,715,380
Options outstanding - Beginning Balance, Weighted Average Exercise Price	$ 24.86	$ 24.62	$ 24.18
Granted, Weighted Average Exercise Price	$ 38.71
Exercised, Weighted Average Exercise Price	$ 24.69	$ 18.69	$ 23.26
Cancelled, Weighted Average Exercise Price	$ 38.69	$ 32.35	$ 29.51
Options outstanding - Ending Balance, Weighted Average Exercise Price	$ 33.70	$ 24.86	$ 24.62
Number of options exercisable, Weighted Average Exercise Price	$ 25.42	$ 24.86	$ 24.62