Stockholders' Equity (Tables)

12 Months Ended

Dec. 31, 2020

Equity [Abstract]

Schedule of Share Grants Activity

The following table represents the share grants stock activity for the year ended December 31, 2020: 

	Nonvested stock			Options
	Number of Shares	Weighted average grant date fair value		Number of Shares	Weighted average grant date fair value
Share grants outstanding at December 31, 2019	534,331	$	71.01	98,756	$	40.71
Granted	136,245	123.89		—	—
Vested or exercised	(200,945)	128.85		(16,286)	32.93
Forfeited	—	—		(8,235)	43.86
Share grants outstanding at December 31, 2020	469,631	$	89.69	74,235	$	42.07

Schedule of Stock Option Outstanding, by Exercise Price Range

The following table summarizes information about stock options outstanding and exercisable at December 31, 2020:

Range of Exercise Price	Shares	Wtd. Avg. Remaining Contractual Life	Wtd. Avg. Exercise Price
$0.00 - $30.00	15,737	3.02	$	26.11
$30.01 - $40.00	20,609	5.18	$	39.38
Over $40.00	37,889	6.45	$	47.74
	74,235	4.91	$	42.07

Summary of Shares Issued Under Employee Stock Purchase Plan

The following table represents the shares issued during 2020, 2019, and 2018, under the Employee Stock Purchase Plan:

Number of
Shares Weighted Average
Per Share Price

Shares available as of December 31, 2017	171,069
Shares issued in 2018	18,725	$	71.12
Shares issued in 2019	19,895	$	103.84
Shares issued in 2020	14,313	$	152.10
Shares available as of December 31, 2020	118,136