Employee Benefit Plans

Share-based Compensation: As of June 30, 2014, we had approximately 7.1 million share-based awards outstanding, including common stock options, restricted stock units and performance stock units which are detailed below. In addition, we had approximately 1.4 million share-based awards available for grant. We recorded share-based compensation expense as follows:



	For the three months ended June 30,				For the six months ended June 30,
	2014		2013		2014		2013
	(in millions)
Share-based compensation expense	$	5.5	$	3.4	$	8.7	$	5.2

Stock options: The following table summarizes information related to our common stock options:



	Number of Stock Options		Weighted Average Exercise Price
Options outstanding at January 1, 2014	5,509,246		$	14.01
Granted	711,380		$	23.47
Exercised	(302,078	)	$	13.03
Canceled or forfeited	(218,950	)	$	18.07
Options outstanding at June 30, 2014	5,699,598		$	15.11
Options exercisable at June 30, 2014	3,016,460		$	12.46
Expected to vest after June 30, 2014	2,041,655		$	18.43

The unamortized compensation costs not yet expensed related to stock options totaled approximately $19.8 million at June 30, 2014 and the weighted average period over which the costs are expected to be recognized is approximately two years. The aggregate amount of cash we received from the exercise of stock options was $4.1 million and $2.3 million for the six months ended June 30, 2014 and 2013, respectively. The associated shares were newly issued common stock. The following information is provided for our stock options:



	For the six months ended June 30,
	2014		2013
Weighted-average grant date fair value	$	9.08	$	9.94

Restricted Stock Units: The following table summarizes information related to our restricted stock units:



	Number of Shares		Weighted Average Grant Date Fair Value
Unvested shares at January 1, 2014	629,518		$	20.11
Granted	424,678		$	23.60
Vested	(120,638	)	$	18.65
Canceled or forfeited	(62,190	)	$	21.93
Unvested shares at June 30, 2014	871,368		$	22.08

Unamortized compensation costs not yet expensed attributable to non-vested shares totaled approximately $17.2 million at June 30, 2014 and the weighted average period over which the costs are expected to be recognized is approximately two years.

Performance Stock Units: The following table summarizes information related to our performance stock units:



	Number of Shares	Weighted Average Grant Date Fair Value
Unvested shares at January 1, 2014	431,858	$	22.79
Granted	123,283	$	26.50
Canceled or forfeited	—	$	—
Unvested shares at June 30, 2014	555,141	$	23.61