Earnings Per Share (Tables)

9 Months Ended

Sep. 30, 2019

Earnings Per Share [Abstract]

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

The following table sets forth the computation of basic and diluted earnings per share on net income (in thousands, except per share information):

	Three months ended September 30,				Nine months ended September 30,
	2019		2018		2019		2018
Earnings:
Net income (numerator for basic and diluted calculations)	$	262,765	$	301,199	$	634,970	$	605,803
Shares:
Weighted average outstanding shares (denominator for basic calculation)	62,666		63,279		62,701		63,941
Equivalent shares from outstanding stock options	1,123		1,017		1,218		1,189
Denominator for diluted calculation	63,789		64,296		63,919		65,130
Earnings per share:
Basic	$	4.19	$	4.76	$	10.13	$	9.47
Diluted	$	4.12	$	4.68	$	9.93	$	9.30

Schedule Of Earnings Per Share Basic And Diluted By Common Class [Text Block]

The following table presents approximate amounts of stock options and performance contingent shares excluded from the calculation of common equivalent shares (in thousands):

	Three months ended September 30,		Nine months ended September 30,
	2019	2018	2019	2018
Excluded from common equivalent shares:
Stock options	139	227	416	349
Performance contingent shares	258	276	182	256