10. STOCK-BASED COMPENSATION

Expense


	Three Months Ended September 30,				Nine Months Ended September 30,
(in thousands)	2018		2017		2018		2017
Cost of revenues	$	4,319	$	3,613	$	12,277	$	10,913
Selling and marketing		6,198		3,976		16,895		11,482
Research and development		3,917		3,420		11,356		10,306
General and administrative		1,974		2,480		7,045		7,228

	$	16,408	$	13,489	$	47,573	$	39,929

Income tax benefit	$	(3,555)	$	(4,129)	$	(10,037)	$	(12,231)

The Company recognizes stock-based compensation using the accelerated recognition method, treating each vesting tranche as if it were an individual grant. As of September 30, 2018, the Company had, net of estimated forfeitures, $74.2 million of unrecognized stock-based compensation expense, related to all unvested restricted stock units (“RSUs”) and stock options, which was expected to be recognized over a weighted-average period of 2.2 years.

Grants

The Company granted the following stock-based compensation awards:


	Nine Months Ended September 30,
(in thousands)	Shares		Total Fair Value
RSUs⁽¹⁾		1,117	$	65,569
Non-qualified stock options		1,623	$	29,372

⁽¹⁾

Includes approximately 0.1 million RSUs which were granted in connection with the election by certain employees to receive 50% of their 2018 target incentive compensation under the Company’s Corporate Incentive Compensation Plan in the form of RSUs instead of cash. Stock-based compensation of approximately $8.2 million associated with this RSU grant is expected to be recognized over a one-year period beginning on the grant date.

RSU vestings and stock option exercises

During the nine months ended September 30, 2018, 1.2 million shares of common stock were issued due to stock option exercises and RSU vestings under the Company’s stock-based compensation plans.