Quarterly Financial Data (Tables)

12 Months Ended

Dec. 31, 2016

Quarterly Financial Information Disclosure [Abstract]

Schedule of Quarterly Financial Information [Table Text Block]

A summary of the company's consolidated quarterly results of operations is as follows:

	First Quarter		Second Quarter		Third Quarter		Fourth Quarter
2016
Sales	$	5,474,177	$	5,972,101	$	5,936,092	$	6,442,891
Gross profit		748,898		798,791		773,162		823,348
Net income attributable to shareholders		106,235		134,270		117,727		164,518
Net income per share (a):
Basic	$	1.16	$	1.46	$	1.29	$	1.84
Diluted	$	1.14	$	1.45	$	1.28	$	1.81
2015
Sales	$	5,002,385	$	5,829,989	$	5,698,304	$	6,751,342
Gross profit		685,322		768,595		742,367		838,966
Net income attributable to shareholders		106,058		123,932		109,244		158,492
Net income per share (a):
Basic	$	1.11	$	1.30	$	1.16	$	1.71
Diluted	$	1.09	$	1.28	$	1.15	$	1.69

(a) Quarterly net income per share is calculated using the weighted-average shares outstanding during each quarterly period, while net income per share for the full year is calculated using the weighted-average shares outstanding during the year. Therefore, the sum of the net income per share for each of the four quarters may not equal the net income per share for the full year.