Stock-Based Awards (Tables)

12 Months Ended

Dec. 31, 2017

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Summary of stock option activity

The Company has granted stock options, which vest upon meeting service conditions. The following table summarizes the stock option activity which contain only service conditions, under the Company’s 1999, 2009 and 2010 Plans (in thousands, except per share and term information):

	Shares		Weighted Average Exercise Price		Weighted Average Remaining Contractual Term	Aggregate Intrinsic Value (1)
Outstanding, December 31, 2016	6,041		$	32.01	6.2	$	74,989
Granted	—		—
Exercised	(413	)	16.38
Forfeited	(334	)	35.71
Outstanding, December 31, 2017	5,294		32.99		5.3	40,122

	Shares	Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term	Aggregate Intrinsic Value (1)
Exercisable at December 31, 2017	4,934	$	32.60	5.2	$	39,951
Vested and expected to vest at December 31, 2017	5,280	32.98		5.3	40,113

(1) Based on the Company’s closing stock price of $35.33 on December 31, 2017 and $42.31 on December 31, 2016.

Schedule of stock options outstanding and exercisable

The following table summarizes information about stock options, which contain only service conditions, under the Company’s equity incentive plans at December 31, 2017 (in thousands except term information):

	Options Outstanding at  December 31, 2017		Options Exercisable at December 31, 2017
	Number of Options	Weighted Average Remaining Contractual Term (in years)	Number of Options	Weighted Average Remaining Contractual Term (in years)
Range of Exercise Prices
$0.34 to $1.65	92	1.9	92	1.9
$5.93 to $8.88	677	2.9	677	2.9
$12.54 to $15.41	132	3.7	132	3.7
$16.24 to $18.82	305	4.0	305	4.0
$20.85 to $23.94	552	4.4	552	4.4
$27.55 to $31.44	207	5.6	193	5.5
$31.64 to $36.15	835	6.8	633	6.6
$38.03 to $45.76	1,093	6.1	1,036	6.0
$46.20 to $56.05	1,401	6.1	1,314	6.1
	5,294	5.3	4,934	5.2

Schedule of restricted stock unit activity

Restricted stock unit activity for the year ended December 31, 2017 under the Company’s equity incentive plans is summarized as follows (shares in thousands):

	Number of Shares		Weighted Average Grant Date Fair Value
Outstanding at December 31, 2016	3,254		$	36.35
Granted	1,938		37.99
Forfeited	(367	)	36.04
Vested	(1,035	)	36.34
Outstanding at December 31, 2017	3,790		$	37.22

Summary of issuances of awards under new compensation award structure

The following table summarizes the Company’s issuances of awards under the new compensation award structure:

Grant Date	Performance Measures	Vesting Term	Performance Period	# of Shares at Target	# of Shares at Maximum	Grant Date Fair Value per share
July 2016	(a) the Company meeting certain revenue and cash flow targets through December 31, 2018 and (b) the recipient continuing to provide services to the Company through the end of June 2019	Three years	Fiscal years 2016, 2017 and 2018	166,600	499,800	$	38.67
March 2017	(a) the Company meeting certain revenue and cash flow targets through December 31, 2019 and (b) the recipient continuing to provide services to the Company through the end of March 2020	Three years	Fiscal years 2017, 2018 and 2019	185,270	555,810	$	41.73

Summary of stock-based compensation expense

Stock-based compensation expense related to stock options, restricted stock units, the ESPP and performance-based restricted stock units is included in the following line items in the accompanying Consolidated Statements of Operations for the years ended December 31, 2017, 2016 and 2015 (in thousands):

	Years Ended December 31,
	2017		2016		2015
Cost of revenue	$	4,904	$	4,732	$	3,887
Sales and marketing	28,427		25,642		23,604
Research and development	9,630		7,586		6,010
General and administrative	22,869		16,739		9,580
Total	$	65,830	$	54,699	$	43,081