Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2011

Summary of Significant Accounting Policies

Fair value of stock options has been estimated at the date of grant using the Black-Scholes option-pricing model with the following weighted-average assumptions:

	2011		2010		2009
Risk free interest rate	1.7	%	2.2	%	2.2	%
Expected life	4.6 years		5.6 years		5.6 years
Expected volatility	28.0	%	33.0	%	34.0	%
Expected dividend yield	0.1	%	0.1	%	0.2	%