Share Repurchase Program (Tables)

12 Months Ended

Dec. 31, 2017

Proceeds from (Repurchase of) Equity [Abstract]

Schedule of shares repurchased

	For the Year Ended   December 31,
	2017		2016
Shares repurchased	9,301		5,698
Average price per share	$	233.57	$	264.21
Total investment	$	2,172,437	$	1,505,371