Stock-Based Compensation - Stock Option Activity Under Equity Incentive Plans (Detail) (Stock Options [Member], USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Outstanding, Beginning balance	20,655
Number of Shares, Options granted	7,713
Number of Shares, Options exercised	(4,852)
Number of Shares, Options forfeited and canceled	(1,521)
Number of Shares, Outstanding, Ending balance	21,995
Number of Shares, Vested and Expected to Vest	21,338
Number of Shares, Exercisable	13,007
Weighted-Average Exercise Price per Share, Outstanding, Beginning balance	$ 9.06
Weighted-Average Exercise Price per Share, Options granted	$ 13.96
Weighted-Average Exercise Price per Share, Options exercised	$ 9.43
Weighted-Average Exercise Price per Share, Options forfeited and Canceled	$ 11.89
Weighted-Average Exercise Price per Share, Outstanding, Ending balance	$ 10.50
Weighted-Average Exercise Price per Share, Vested and expected to vest	$ 10.41
Weighted-Average Exercise Price per Share, Exercisable	$ 8.90
Weighted-Average Remaining Contractual Life, Outstanding	4 years 11 months 16 days
Weighted-Average Remaining Contractual Life, Vested and expected to Vest	4 years 10 months 21 days
Weighted-Average Remaining Contractual Life, Exercisable	3 years 5 months 19 days
Aggregate Intrinsic Value, Outstanding	$ 112,549
Aggregate Intrinsic Value, Vested and expected to Vest	111,071
Aggregate Intrinsic Value, Exercisable	$ 85,839