Earnings Per Share (Tables)

12 Months Ended

Dec. 31, 2017

Earnings Per Share [Abstract]

Reconciliation Between Basic and Diluted Earnings Per Share

A reconciliation between basic and diluted earnings per share is as follows (in thousands, except per share data):

	Year Ended December 31,
	2017		2016		2015
Net income for basic and diluted earnings per share	$	1,625,133	$	1,283,388	$	665,783
Weighted-average common shares outstanding	214,617		215,393		219,537
Dilutive effect of stock-based awards	1,077		923		1,152
Diluted weighted-average shares outstanding	215,694		216,316		220,689
Basic earnings per share:
Net income	$	7.57	$	5.96	$	3.03
Diluted earnings per share:
Net income	$	7.53	$	5.93	$	3.02