Stockholders' Equity (Tables)

3 Months Ended

Mar. 31, 2020

Stockholders' Equity Note [Abstract]

Schedule of Dividends Paid Previously or Declared

The following table presents the dividends either paid previously or declared by our board of directors for future payment on a per share basis:



	2020		2019
First quarter	$	0.250	0.215
Second quarter	0.250		0.215
Third quarter			0.220
Fourth quarter			0.220
Total	$	0.500	0.870

Stock Options Granted

The following tables summarize the details of options granted under our stock option plans that were outstanding as of March 31, 2020, and the assumptions used to value these grants. All such grants were effective at the close of business on the date of grant.



	Options Granted	Option Exercise (Strike) Price		Closing Stock Price on Date of Grant		March 31, 2020
Date of Grant	Options Granted	Option Exercise (Strike) Price		Closing Stock Price on Date of Grant		Options Outstanding	Options Exercisable
January 2, 2020	902,263	$	38.00	$	37.230	900,685	24,964
January 2, 2019	1,316,924	$	26.00	$	25.705	1,254,462	29,010
January 2, 2018	1,087,936	$	27.50	$	27.270	955,006	324,848
January 3, 2017	1,529,578	$	23.50	$	23.475	1,140,844	523,176
April 19, 2016	1,690,880	$	23.00	$	22.870	1,202,444	435,348
April 21, 2015	1,786,440	$	21.00	$	20.630	798,495	411,775
April 22, 2014	1,910,000	$	28.00	$	25.265	560,340	318,480
April 16, 2013	410,000	$	27.00	$	24.625	89,472	50,722
April 17, 2012	2,470,000	$	27.00	$	24.505	446,480	339,678
April 19, 2011	820,000	$	17.50	$	15.890	5,000	5,000
Total	13,924,021					7,353,228	2,463,001

Fair Value Assumptions for Options Granted



Date of Grant	Risk-free Interest Rate		Expected Life of Option in Years	Expected Dividend Yield		Expected Stock Volatility		Estimated Fair Value of Stock Option
January 2, 2020	1.7	%	5.00	2.4	%	25.70	%	$	6.81
January 2, 2019	2.5	%	5.00	2.9	%	23.96	%	$	4.40
January 2, 2018	2.2	%	5.00	2.3	%	23.45	%	$	5.02
January 3, 2017	1.9	%	5.00	2.6	%	24.49	%	$	4.20
April 19, 2016	1.3	%	5.00	2.6	%	26.34	%	$	4.09
April 21, 2015	1.3	%	5.00	2.7	%	26.84	%	$	3.68
April 22, 2014	1.8	%	5.00	2.0	%	28.55	%	$	4.79
April 16, 2013	0.7	%	5.00	1.6	%	37.42	%	$	6.33
April 17, 2012	0.9	%	5.00	1.4	%	39.25	%	$	6.85
April 19, 2011	2.1	%	5.00	1.6	%	39.33	%	$	5.60

Reconciliation of Denominators used in Computation of Basic and Diluted Earnings Per Share

The following tables present a reconciliation of the denominators used in the computation of basic and diluted earnings per share and a summary of the options to purchase shares of common stock which were excluded from the diluted earnings per share calculation because they were anti-dilutive:



	Three-month Period
Reconciliation	2020	2019
Basic weighted average shares outstanding	573,904,156	572,172,602
Weighted shares assumed upon exercise of stock options	1,414,674	821,360
Diluted weighted average shares outstanding	575,318,830	572,993,962

Anti-Dilutive Options Excluded

Three-month Period

Summary of Anti-dilutive Options Excluded

Options to purchase shares of common stock

Weighted average exercise prices of options