Stockholders' Equity (Tables)

12 Months Ended

Dec. 31, 2016

Stockholders' Equity Note [Abstract]

Summary of Activity Related to Stock Option Plans

A summary of the activities related to the Company’s stock option plans, as adjusted for the Stock Split, is as follows:

	Shares Available for Grant		Options Outstanding				Weighted- Average Remaining Contractual Term (in Years)	Aggregate Intrinsic Value (in Thousands)
			Number of Shares		Weighted- Average Exercise Price (per Share)
Balances as of December 31, 2013	23,844,219		24,688,286		$	13.61
Granted	(3,819,011	)	3,819,011		57.55
Exercised	—		(5,661,880	)	10.81
Balances as of December 31, 2014	20,025,208		22,845,417		$	21.65
Granted	(3,179,892	)	3,179,892		82.67
Exercised			(5,029,553	)	15.38
Balances as of December 31, 2015	16,845,316		20,995,756		$	32.39
Granted	(3,555,363	)	3,555,363		102.03
Exercised	—		(2,113,772	)	17.48
Balances as of December 31, 2016	13,289,953		22,437,347		$	44.83	6.18	$	1,772,185
Vested and exercisable at December 31, 2016			22,437,347		$	44.83	6.18	$	1,772,185

Summary of Assumptions Used to Value Stock Option Grants Using Lattice-Binomial Model

The following table summarizes the assumptions used to value option grants using the lattice-binomial model and the valuation data:

	Year Ended December 31,
	2016			2015			2014
Dividend yield	—		%	—		%	—		%
Expected volatility	40% - 50%			36% - 53%			41% - 48%
Risk-free interest rate	1.57% - 2.04%			2.03% - 2.29%			2.39% - 2.83%
Suboptimal exercise factor	2.48			2.47 - 2.48			2.66 - 5.44
Valuation data:
Weighted-average fair value (per share)	$	48.85		$	39.22		$	30.17
Total stock-based compensation expense (in thousands)	173,675			124,725			115,239
Total income tax impact on provision (in thousands)	65,173			47,125			43,999