Equity Incentive Plans - Summary of Stock Option and RSU Activity (Detail) - 2010 Equity Incentive Plan [Member] $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2017 USD ($) $ / shares shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Options, Beginning Balance | shares	12,875,422
Number of Options, Granted | shares	1,163,678
Number of Options Exercised or released | shares	(2,324,871)
Number of Options, Cancelled | shares	(833,204)
Number of Options, Ending Balance | shares	10,881,025
Number of Options, Vested and expected to vest | shares	10,881,025
Number of Options, Exercisable and vested | shares	8,029,228
Weighted Average Exercise Price, Beginning Balance | $ / shares	$ 96.50
Weighted Average Exercise Price, Granted | $ / shares	310.13
Weighted Average Exercise Price, Exercised or released | $ / shares	81.04
Weighted Average Exercise Price, Cancelled | $ / shares	327.33
Weighted Average Exercise Price, Ending Balance | $ / shares	105.56
Weighted Average Exercise Price, Vested and expected to vest | $ / shares	105.56
Weighted Average Exercise Price, Exercisable and vested | $ / shares	$ 77.56
Weighted Average Remaining Contractual Life (Years), Balance	5 years 3 months 18 days
Weighted Average Remaining Contractual Life (Years), Vested and expected to vest	5 years 3 months 18 days
Weighted Average Remaining Contractual Life (Years), Exercisable and vested	4 years 8 months 12 days
Aggregate Intrinsic Value, Beginning Balance | $	$ 2,300
Aggregate Intrinsic Value, Exercised or released | $	540
Aggregate Intrinsic Value, Vested and expected to vest | $	2,300
Aggregate Intrinsic Value, Exercisable and vested | $	$ 1,910
Restricted stock units [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of RSUs, Beginning Balance | shares	4,082,089
Number of RSUs, Granted | shares	3,073,404
Number of RSUs, Exercised or released | shares	(1,561,889)
Number of RSUs, Cancelled | shares	(904,294)
Number of RSUs, Ending Balance | shares	4,689,310
Number of RSUs, Vested and expected to vest | shares	4,689,310
Weighted Average Grant Date Fair Value, Beginning Balance | $ / shares	$ 207.11
Weighted Average Grant Date Fair Value, Granted | $ / shares	308.71
Weighted Average Grant Date Fair Value, Exercised or released | $ / shares	216.46
Weighted Average Grant Date Fair Value, Cancelled | $ / shares	233.59
Weighted Average Grant Date Fair Value, Ending Balance | $ / shares	265.43
Weighted Average Grand Date Fair Value, Vested and Expected to Vest | $ / shares	$ 265.43