Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2019

Share-based Payment Arrangement, Noncash Expense [Abstract]

Schedule Of Range Of Exercise Prices For Outstanding Options

For options outstanding at December 31, 2019, the options had the following range of exercise prices:

Range of Prices	Options  Outstanding	Weighted Average Remaining  Contractual Life (Years)
$10.26 - $30.05	264,334	1.0
$40.38 - $44.42	218,047	6.1
$45.70 - $61.87	295,620	6.5
$63.98 - $68.18	145,171	4.7
$79.83 - $107.75	462,776	8.8

Schedule Of Option Activity And Changes

Option activity and changes during the year ended December 31, 2019 were as follows:

	Options		Weighted Average Exercise Price		Weighted Average Remaining Term (Years)	Aggregate Intrinsic Value
Outstanding at December 31, 2018	1,115,954		$	54.82
Granted	296,598		79.83
Exercised	(18,635	)	35.04
Cancelled	(7,969	)	79.94
Outstanding at December 31, 2019	1,385,948		$	60.29	5.9	$	23
Exercisable at December 31, 2019	888,093		$	47.64	4.5	$	22

Schedule Of Weighted Average Value And Assumptions For Fair Value Of Options

The Company used the Black-Scholes option pricing model to value its options. The table below presents the weighted average value and assumptions used in determining each option's fair value. Volatility was calculated using historical trends of the Company's common stock price.

	Stock Option Grants
	Year Ended December 31,
	2019			2018			2017
Weighted average fair value	$	21.02		$	28.94		$	15.84
Risk-free interest rate	2.5		%	2.7		%	2.1		%
Expected life in years	5			5			5
Expected volatility	28.9		%	27.6		%	29.2		%
Expected dividend yield	1.2		%	0.7		%	1.2		%

Schedule Of Non-Vested Restricted Stock Award Activity And Changes

Non-vested liability classified restricted stock awards as of December 31, 2019 and changes during the year ended December 31, 2019 were as follows:

	Number of Units		Weighted Average Fair Value
Non-vested at December 31, 2018	49,528		$	66.46
Vested	(49,292	)	68.22
Cancelled	(236	)	76.77
Non-vested at December 31, 2019	—		—

Non-vested restricted stock units as of December 31, 2019 and changes during the year ended December 31, 2019 were as follows:

	Number of Units		Weighted Average Grant Date Fair Value
Non-vested at December 31, 2018	702,789		$	65.79
Granted	205,517		77.59
Vested	(415,593	)	56.70
Forfeited	(29,430	)	73.28
Non-vested at December 31, 2019	463,283		$	78.69

Share-based Payment Arrangement, Performance Shares, Activity [Table Text Block]

	Number of Units		Weighted Average Grant Date Fair Value
Non-vested at December 31, 2018	—		$	—
Granted	78,328		114.38
Vested	—		—
Forfeited	(1,111	)	114.38
Non-vested at December 31, 2019	77,217		$	114.38

Share-based Compensation Arrangements by Share-based Payment Award, Performance-Based Units, Vested and Expected to Vest [Table Text Block]

	Year Ended December 31, 2019 Performance Stock Units
Risk-free interest rate	2.5		%
Expected life in years	2.88
Expected volatility of Westlake Chemical Corporation common stock	30.3		%
Expected volatility of peer companies	14.5% - 47.8%
Average correlation coefficient of peer companies	0.49
Grant date fair value	$	114.38