Shared Based Awards (Tables)

12 Months Ended

Dec. 31, 2011

Share Based Awards [Abstract]

Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block]

	Year ended December 31,
	2011			2010			2009
Expected term (in years)	3.0			3.4			5.8
Expected stock price volatility	35.3		%	40.2		%	37.4		%
Risk-free interest rate	0.9		%	0.8		%	2.4		%
Expected dividend yield	—		%	—		%	—		%
Weighted average grant price	$	43.27		$	34.70		$	35.24
Weighted average grant date fair value	$	10.72		$	10.18		$	12.98

Schedule of Share-based Compensation, Stock Options, Activity [Table Text Block]

A summary of the Company’s stock option activity as of and for the year ended December 31, 2011 is as follows:

	Shares		Weighted Average Exercise Price
Outstanding at December 31, 2010	2,919,194		$	29.77
Granted	290,000		$	43.27
Exercised	(459,266	)	$	17.36
Forfeited or expired	(4,500	)	$	27.48
Outstanding at December 31, 2011	2,745,428		$	33.28
Exercisable at December 31, 2011	1,765,397		$	31.97
Available for grant at December 31, 2011:
2011 Plan	786,700

Schedule of Share-based Payment Award, Employee Stock Purchase Plan, Valuation Assumptions [Table Text Block]

	Year ended December 31,
	2011		2010		2009
Expected term (in years)	0.5		0.5		0.5
Expected stock price volatility	26.0	%	26.5	%	48.3	%
Risk-free interest rate	0.4	%	0.2	%	0.4	%
Expected dividend yield	—	%	—	%	—	%