Net Income Per Share (Tables)

12 Months Ended

Dec. 31, 2016

Earnings Per Share [Abstract]

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

The following table presents the computation of net income per share on a basic and diluted basis for the years ended December 31 (shares in thousands):

	2016		2015		2014
Net income attributable to shareholders	$	522,750	$	497,726	$	498,045
Weighted-average shares outstanding - basic	90,960		94,608		98,675
Net effect of various dilutive stock-based compensation awards	1,073		1,078		1,272
Weighted-average shares outstanding - diluted	92,033		95,686		99,947
Net income per share:
Basic	$	5.75	$	5.26	$	5.05
Diluted (a)	$	5.68	$	5.20	$	4.98

(a) Stock-based compensation awards for the issuance of 766 shares, 658 shares, and 294 shares for the years ended December 31, 2016, 2015, and 2014, respectively, were excluded from the computation of net income per share on a diluted basis as their effect was anti-dilutive.