Stockholder's Equity (Tables)

9 Months Ended

Sep. 30, 2018

Equity [Abstract]

Nonvested Stock Activity

The following table represents the nonvested stock activity for the nine months ended September 30, 2018:

	Restricted stock				Options
	Number of shares		Weighted average grant date fair value		Number of shares		Weighted average grant date fair value
Nonvested shares outstanding as of December 31, 2017	529,465		$	37.34	—		$	—
Granted	257,175		$	64.11	—		$	—
Acquired	—		$	—	270,710		$	36.48
Vested or exercised	(211,355	)	$	37.78	(93,532	)	$	34.55
Nonvested shares outstanding as of September 30, 2018	575,285		$	49.66	177,178		$	37.50

Shares of Common Stock Issued During 2016 Under Employee Stock Purchase Plan

The table below details the shares of common stock issued during 2018:

	Number of shares	Per share price
Shares available as of December 31, 2017	171,069
Shares issued during the three months ended March 31, 2018	5,534	$	58.19
Shares issued during the three months ended June 30, 2018	5,171	$	58.48
Shares issued during the three months ended September 30, 2018	4,682	$	81.31
Shares available as of September 30, 2018	155,682