Share Repurchase Program (Tables)

9 Months Ended

Sep. 30, 2017

Proceeds from (Repurchase of) Equity [Abstract]

Schedule of shares repurchased

	For the Three Months Ended   September 30,				For the Nine Months Ended   September 30,
	2017		2016		2017		2016
Shares repurchased	2,743		367		8,047		3,673
Average price per share	$	200.70	$	281.04	$	235.26	$	261.32
Total investment	$	550,530	$	102,941	$	1,893,068	$	959,743