Equity Compensation Plans (Tables)

9 Months Ended

Sep. 30, 2012

Fair Value of Stock Options Granted Using Black- Scholes Valuation Model

The fair value of the stock options granted during the nine months ended September 30, 2012 and 2011 was estimated using a Black-Scholes valuation model that uses the weighted average assumptions noted in the following table:

	2012			2011
Option pricing model		Black-Scholes			Black-Scholes
Expected volatility		32.25	%		30.44	%
Risk-free interest rate		0.90	%		2.21	%
Expected term in years		4.6			5.1
Dividend yield		0.00	%		0.00	%
Weighted average grant date fair value per stock option	$	13.59		$	10.42

Options Outstanding Under Incentive Plan and Option Plan

A summary of options outstanding under the Incentive Plan and the Option Plan as of December 31, 2011 and September 30, 2012 and changes during the interim period is presented below:

	Number of Options			Weighted Average Exercise  Price		Aggregate Intrinsic Value
Outstanding at December 31, 2011		18,896,405		$	16.55	$	445,510
Granted		944,015		$	47.33
Exercised		(4,707,394	)	$	7.33	$	178,912
Cancelled or expired		(309,840	)	$	14.81
Outstanding at September 30, 2012		14,823,186		$	20.87	$	396,444
Options exercisable at September 30, 2012		9,603,360		$	16.58	$	297,975
Options exercisable at December 31, 2011		12,153,311		$	12.35	$	337,647

Summary of Restricted Stock Activity Under Incentive Plan

A summary of the status of the restricted stock awarded under the Incentive Plan as of December 31, 2011 and September 30, 2012 and changes during the interim period is presented below:

	Number of Shares			Weighted Average Grant Date Fair Value
Outstanding at December 31, 2011		145,634		$	33.32
Granted		236,280		$	47.04
Vested		(37,632	)	$	33.44
Forfeited		(6,518	)	$	40.62
Outstanding at September 30, 2012		337,764		$	42.74