Quarterly Data (Tables)

12 Months Ended

Dec. 31, 2017

Quarterly Financial Information Disclosure [Abstract]

Quarterly Data [Table Text Block]

							Net Earnings
Quarter	Revenue		Gross Profit		Earnings		Per Share - Basic		Per Share - Diluted
2017
First	$	1,813,372	$	661,175	$	172,247	$	1.11	$	1.09
Second	1,993,351		749,446		164,058		1.05		1.04
Third	2,006,275		744,333		178,912		1.15		1.14
Fourth	2,017,438		735,423		296,448		1.90		1.88
	$	7,830,436	$	2,890,377	$	811,665	$	5.21	$	5.15
2016
First	$	1,622,273	$	589,264	$	99,356	$	0.64	$	0.64
Second	1,686,345		631,213		118,290		0.76		0.76
Third	1,707,763		631,788		130,084		0.84		0.83
Fourth	1,777,961		619,704		161,162		1.04		1.03
	$	6,794,342	$	2,471,969	$	508,892	$	3.28	$	3.25