Computation of Earnings Per Share (Tables)

12 Months Ended

Dec. 31, 2012

Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]

The following table sets forth the reconciliation of the basic and diluted earnings per share computations (in thousands, except per share amounts) for the years ended December 31:

	2012		2011		2010
Numerator:
Net income used for calculating basic and diluted earnings per common share	$	165,903	$	136,902	$	96,285
Denominator: (1)
Weighted average number of common shares used in the calculation of basic earnings per share		93,444		96,019		95,747
Common share equivalents associated with stock-based compensation plans		2,398		2,827		4,087
Shares used in the calculation of diluted earnings per share		95,842		98,846		99,834
Earnings per share:
Basic	$	1.78	$	1.43	$	1.01
Diluted	$	1.73	$	1.39	$	0.96

Schedule of Earnings Per Share Reconciliation [Table Text Block]

The following table presents the number of common share equivalents that were not included in the computation of diluted EPS in the table above because the effect would have been antidilutive. During periods with net income, these common share equivalents were antidilutive because their exercise price was greater than the average market value of a share of Common Stock during the period.

	2012		2011		2010
Antidilutive common share equivalents as of December 31 (in millions):		0.7		0.5		0.5
Average market price per share of Common Stock during the year	$	43.80	$	37.53	$	26.35