Share Repurchase Program (Tables)

6 Months Ended

Jun. 30, 2017

Proceeds from (Repurchase of) Equity [Abstract]

Schedule of shares repurchased

	For the Three Months Ended   June 30,				For the Six Months Ended   June 30,
	2017		2016		2017		2016
Shares repurchased	3,475		2,075		5,304		3,306
Average price per share	$	245.26	$	262.17	$	253.13	$	259.14
Total investment	$	852,226	$	544,165	$	1,342,538	$	856,802