Equity Incentive Plans - Summary of Stock Option and RSU Activity Under Plan (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares Available for Grant, Beginning Balance	1,720,505	469,531	9,919,107
Shares Available for Grant, Additional options reserved	3,077,274	3,426,428	1,064,046
Shares Available for Grant, Granted	(2,525,246)	(3,345,899)	(11,854,941)
Shares Available for Grant, Cancelled	556,765	1,170,445	1,341,319
Shares Available for Grant, Ending Balance	2,836,084	1,720,505	469,531
Shares Available for Grant, Traded for taxes	6,786
Number of Options, Beginning Balance	22,640,942	25,007,776	15,806,663
Number of Options, Granted	1,432,171	2,643,821	11,854,941
Number of Options, Exercised	(2,266,697)	(3,852,673)	(1,312,439)
Number of Options, Cancelled	(433,456)	(1,157,982)	(1,341,389)
Number of Options, Ending Balance	21,372,960	22,640,942	25,007,776
Weighted Average Exercise Price, Beginning Balance	$ 26.70	$ 21.20	$ 13.35
Weighted Average Exercise Price, Granted	$ 181.56	$ 74.17	$ 31.18
Weighted Average Exercise Price, Exercised	$ 31.80	$ 21.42	$ 12.52
Weighted Average Exercise Price, Cancelled	$ 56.25	$ 36.47	$ 25.51
Weighted Average Exercise Price, Ending Balance	$ 35.93	$ 26.70	$ 21.20
Number of RSUs, Beginning Balance	677,584
Number of RSUs, Granted	1,093,075	702,078
Number of RSUs, Cancelled	(123,309)	(12,463)
Number of RSUs, Released	(167,240)	(12,031)
Number of RSUs, Ending Balance	1,480,110	677,584
Restricted stock units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted Average Grant Date Fair Value, Beginning Balance	$ 155.41
Weighted Average Grant Date Fair Value, Granted	$ 223.66	$ 155.51
Weighted Average Grant Date Fair Value, Cancelled	$ 187.90	$ 154.92
Weighted Average Grant Date Fair Value, Released	$ 155.70	$ 160.98
Weighted Average Grant Date Fair Value, Ending Balance	$ 203.08	$ 155.41