Stock-Based Compensation

3 Months Ended

Mar. 31, 2016

The Company measures compensation cost for all stock awards at fair value on the date of grant and recognizes compensation cost, net of estimated forfeitures, over the requisite service period for awards expected to vest. The Company recognized $9.9 million and $6.8 million of pretax stock-based compensation expense during the three months ended March 31, 2016 and 2015, respectively.

The following table summarizes the changes in the number of shares of common stock underlying outstanding stock options for the three months ended March 31, 2016 (in millions, except weighted-average exercise prices):



	Options Outstanding and Exercisable		Weighted-Average Exercise Price		Aggregate Intrinsic Value Exercisable
Outstanding at December 31, 2015	1.2		$	20	$	28.1
Exercised	(0.2	)	17
Outstanding at March 31, 2016	1.0		$	21	$	22.0

The following table summarizes the changes in the number of outstanding restricted stock units for the three months ended March 31, 2016 (shares in millions):

During 2014 and 2015, the Company awarded performance stock units which entitle recipients to shares of the Company’s stock at the end of a three-year vesting period if specified performance or market conditions are achieved (“PSUs”). The PSUs generally entitle recipients to shares of common stock equal to 0% up to 200% of the number of units granted at the vesting date depending on the level of achievement of the specified performance, market and service conditions. As of March 31, 2016, 1.1 million PSUs were outstanding. Based on performance through March 31, 2016, holders of unvested PSUs would be entitled to approximately 1.2 million shares at the vesting date. The PSUs are included in the preceding table as if the holders of PSUs earn shares equal to 100% of the units granted

Restricted Stock Units

Weighted-
Average Grant
Date Fair Value

Outstanding at December 31, 2015

Outstanding at March 31, 2016