Share Based Compensation - Summary of Changes in Number of Shares of Restricted Stock and Restricted Stock Units (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Shares, Outstanding, Beginning balance	472	840	1,250
Shares, Granted	358	131	261
Shares, Cancelled	(31)	(25)	(50)
Shares, Sold/Issued	(165)	(474)	(621)
Shares, Outstanding, Ending balance	634	472	840
Weighted Average Grant Date Fair Value, outstanding, Beginning balance	$ 28.98	$ 23.15	$ 21.93
Weighted Average Grant Date Fair Value, Granted	$ 92.16	$ 41.69	$ 31.08
Weighted Average Grant Date Fair Value, Cancelled	$ 35.42	$ 33.49	$ 21.00
Weighted Average Grant Date Fair Value, Sold/Issued	$ 30.93	$ 22.05	$ 23.12
Weighted Average Grant Date Fair Value, Outstanding, Ending balance	$ 67.83	$ 28.98	$ 23.15