Share Based Compensation (Tables)

3 Months Ended

Mar. 31, 2012

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Summary Of Expense Related To Share-Based Payments

	Three Months Ended March 31,
	2012		2011
Stock options	$	2,277	$	2,460
Restricted stock		1,557		1,681
Stock-based compensation	$	3,834	$	4,141

Summary Of Total Unrecognized Compensation Cost Related To Stock-Based Compensation

	Unrecognized Compensation Cost		Weighted Average Period  of Expense Recognition (in Years)
Stock options	$	23,368		2.18
Restricted stock		11,503		1.60
Total	$	34,871

Summary Of Changes In The Number Of Shares Of Common Stock Under Option

	Shares			Weighted Average Exercise Price		Options Exercisable at End of Period		Weighted Average Exercise Price of Exercisable Options		Weighted Average Fair Value of Options Granted During the Period	Aggregate Intrinsic Value
Outstanding at December 31, 2011		8,341		$	15.51		4,394	$	10.13		$	119,802
Exercised		(1,019	)		7.77							31,607
Forfeited		(30	)		10.00
Outstanding at March 31, 2012		7,292		$	16.61		3,716	$	11.09		$	161,530
Expected to vest as of March 31, 2012		7,292		$	16.61

Summary Of Changes In The Number Of Shares Of Restricted Stock And Restricted Stock Units

	Shares			Weighted Average Grant Date Fair Value
Unvested at December 31, 2011		840		$	23.15
Granted		41			34.35
Vested		(22	)		29.59
Cancelled		—			—
Unvested at March 31, 2012		859		$	23.52

Stock Options [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Schedule Of Weighted-Average Assumptions

Risk-free interest rate	1.76	%
Dividend yield	—
Expected volatility	39.27	%
Expected life (in years)	4.0

Restricted Stock [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Schedule Of Weighted-Average Assumptions

	Three Months Ended March 31, 2011
Risk-free interest rate		1.25	%
Dividend yield		—
Expected volatility		37.00	%
Expected life (in years)		0.63