Stock Incentive Plans (Tables)

3 Months Ended

Mar. 31, 2019

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Summary of Share-based Awards Available for Grant under 2016 Plan

A summary of share-based awards available for grant under the 2016 Plan is as follows:

	Awards Available for Grant
Balance at December 31, 2017		4,034,152
Additional awards authorized		1,168,865
Awards granted		(666,913	)
Awards forfeited		124,478
Awards withheld for tax purposes		56,710
Balance at December 31, 2018		4,717,292
Additional options authorized		1,218,402
Awards granted		(481,366	)
Awards forfeited		46,222
Awards withheld for tax purposes		33,929
Balance at March 31, 2019		5,534,479

Summary of Stock Option Activity Under 2006 and 2016 Plans

The following table summarizes stock option activity under the 2006 and 2016 Plans:

				Options Outstanding
	Options Outstanding			Weighted- Average Exercise Price Per Share		Weighted- Average Remaining Contractual Life (years)		Aggregate Intrinsic Value (in thousands)
Balance at December 31, 2017		2,601,181		$	12.24		7.17	$	113,958
Options granted		366,928		$	68.32
Options exercised		(798,424	)	$	7.19
Options forfeited		(75,548	)	$	34.30
Balance at December 31, 2018		2,094,137		$	23.20		7.02	$	97,976
Options granted		18,730		$	83.54
Options exercised		(203,552	)	$	10.42
Options forfeited		(23,401	)	$	58.23
Balances at March 31, 2019		1,885,914		$	24.74		6.96	$	95,499
Options exercisable – March 31, 2019		1,230,759		$	13.74		6.30	$	75,343
Options vested and expected to vest – March 31, 2019		1,850,457		$	24.18		6.93	$	94,689