Share Based Payments - Summary of Stock Option Activity and Restricted Stock Unit under all Equity Plans (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Schedule Of Stock Option Activity [Line Items]
Beginning balance, Shares	2,710	2,529	2,371
Granted, Shares	1,397	1,119	820
Exercised, Shares	(592)	(660)	(519)
Canceled or expired, Shares	(259)	(278)	(143)
Ending balance, Shares	3,256	2,710	2,529
Beginning balance, Weighted Average Exercise Price	$ 34.05	$ 25.06	$ 15.34
Granted, Weighted Average Exercise Price	$ 80.78	$ 45.31	$ 43.90
Exercised, Weighted Average Exercise Price	$ 23.91	$ 7.52	$ 2.62
Canceled or expired, Weighted Average Exercise Price	$ 63.30	$ 60.80	$ 53.83
Ending balance, Weighted Average Exercise Price	$ 53.62	$ 34.05	$ 25.06
Exercisable, Weighted Average Exercise Price	$ 34.15
Exercisable and expected to vest, Weighted Average Exercise Price	$ 52.48
Exercisable and expected to vest, Weighted Average Exercise Price	$ 52.48
Exercisable, Number of Shares	1,150
Exercisable and expected to vest, Number of Shares	2,940
Exercisable and expected to vest, Number of Shares	2,940
Restricted Stock Units [Member]
Schedule Of Stock Option Activity [Line Items]
Exercisable and expected to vest, Weighted Average Exercise Price	$ 63.11
Granted, Shares	30
Exercisable and expected to vest, Weighted Average Exercise Price	$ 63.11
Exercised, Shares	0	0	0
Canceled or expired, Shares	0	0	0
Ending balance, Shares	30
Granted, Weighted Average Grant Date Fair Value	$ 63.11
Exercised, Weighted Average Grant Date Fair Value	$ 0	$ 0	$ 0
Canceled or expired, Weighted Average Grant Date Fair Value	$ 0	$ 0	$ 0
Ending balance, Weighted Average Grant Date Fair Value	$ 63.11
Exercisable and expected to vest, Number of Shares	30
Exercisable and expected to vest, Number of Shares	30