Share Based Compensation - Summary of Changes in Number of Shares of Restricted Stock and Restricted Stock Units (Detail) - 6 months ended Jun. 30, 2015 - $ / shares shares in Thousands	Total
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Shares, Unvested, Beginning balance	716
Shares, Granted	89
Shares, Vested	(100)
Shares, Cancelled	(5)
Shares, Unvested, Ending balance	700
Weighted Average Grant Date Fair Value, Unvested, Beginning balance	$ 121.38
Weighted Average Grant Date Fair Value, Granted	155.65
Weighted Average Grant Date Fair Value, Vested	123.33
Weighted Average Grant Date Fair Value, Cancelled	35.78
Weighted Average Grant Date Fair Value, Unvested, Ending balance	$ 126.67