Stockholder's Equity (Tables)

3 Months Ended

Mar. 31, 2018

Equity [Abstract]

Nonvested Stock Activity

The following table represents the nonvested stock activity for the three months ended March 31, 2018:

	Number of shares		Weighted average grant date fair value
Nonvested shares outstanding as of December 31, 2017	529,465		$	37.34
Granted	169,945		$	61.07
Vested	(165,567	)	$	33.91
Nonvested shares outstanding as of March 31,2018	533,843		$	45.96

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 available as of March 31, 2018	165,535