Common Stock

We have 500 million authorized shares of common stock, $0.01 par value. At December 31, 2017 and 2016, there were 0.5 million shares of common stock reserved for issuance pursuant to options granted under our stock option plans.

As of December 31, 2017, there were an aggregate of 1.0 million outstanding time and performance-based RSUs and 2.6 million shares available for grant of stock and options under our 2010 Long Term Incentive Plan.

A summary of the transactions within the Company’s stock option plans follows (shares in thousands):



	Shares		Weighted-Average Exercise Price
Outstanding at December 31, 2016	507		21.37
Granted	105		60.89
Exercised	(63	)	39.72
Canceled	—		—
Outstanding at December 31, 2017	549		26.80
Exercisable at December 31, 2017	480		$	22.04

The following table presents information associated with options as of December 31, 2017 and 2016, and for the years ended December 31, 2017, 2016 and 2015:



	2017		2016		2015
Intrinsic value of options outstanding as of December 31	$	80	$	43
Intrinsic value of options exercisable as of December 31	72		43
Intrinsic value of options exercised	6		4		7
Weighted-average grant date fair value per option	$	84.60	$	—	$	—

In addition to stock options, the Company issues time-based and performance-based RSUs to certain officers and key executives under various plans. The RSUs automatically convert to shares of common stock on a one-for-one basis as the awards vest. The time-based RSUs typically vest over a three year vesting period beginning 12 months from the grant date and thereafter annually on the anniversary of the grant date. The performance-based RSUs vest over the performance period which is currently the calendar year. There were 346 thousand shares of common stock issued upon vesting of RSUs during 2017, net of 227 thousand shares surrendered to satisfy tax obligations. The Company measures the value of RSUs at fair value based on the closing price of the underlying common stock on the grant date. The Company amortizes the fair value of outstanding RSUs as stock-based compensation expense over the requisite service period on a straight-line basis, or sooner if the employee effectively vests upon termination of employment under certain circumstances. For performance-based RSUs, compensation expense is recognized to the extent that the satisfaction of the performance condition is considered probable.

A summary of RSUs granted follows (RSUs in thousands):



	Year Ended December 31,
	2017		2016		2015
RSUs granted	809		901		463
Weighted-average grant date price per unit	$	130.96	$	60.55	$	86.84

As of December 31, 2017, the total pretax compensation cost not yet recognized by the Company with regard to unvested RSUs was $46. The weighted-average period over which this compensation cost is expected to be recognized is 2.1 years.

A summary of RSU activity for the year ended December 31, 2017 follows (RSUs in thousands):



	Stock Units		Weighted-Average Grant Date Fair Value
Nonvested as of December 31, 2016	751		$	71.29
Granted	809		130.96
Vested	(782	)	110.37
Forfeited	(22	)	93.13
Nonvested as of December 31, 2017	756		$	94.07

The total fair value of RSUs vested during the fiscal years ended December 31, 2017, 2016 and 2015 was $101, $39, and $84, respectively.

Stockholders’ Rights Plan. Our stockholders' rights plan expired in accordance with its terms on September 27, 2011. Our Board of Directors elected not to renew or extend the plan.