Stockholders' Equity

3 Months Ended

Mar. 31, 2020

Stockholders' Equity Note [Abstract]

(4) Stockholders' Equity

Dividends

On April 13, 2020, our board of directors declared a dividend of $0.25 per share of common stock to be paid in cash on May 26, 2020 to shareholders of record at the close of business on April 28, 2020. Since 2011, we have paid quarterly dividends. Our board of directors currently intends to continue paying quarterly dividends, provided that any future determination as to payment of dividends will depend on the financial condition and results of operations of the company and such other factors as are deemed relevant by the board of directors.

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

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



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

All of the options in the tables above vest and become exercisable over a period of up to eight years. Generally, each option will terminate approximately nine years after the grant date.

The fair value of each share-based option is estimated on the date of grant using a Black-Scholes valuation method that uses the assumptions listed above. The risk-free interest rate is based on the U.S. Treasury rate over the expected life of the option at the time of grant. The expected life is the average length of time over which we expect the employee groups will exercise their options, which is based on historical experience with similar grants. The dividend yield is estimated over the expected life of the option based on our current dividend payout, historical dividends paid, and expected future cash dividends. Expected stock volatilities are based on the movement of our stock price over the most recent historical period equivalent to the expected life of the option.

Compensation expense equal to the grant date fair value is recognized for all of these awards over the vesting period. The stock-based compensation expense for the three-month periods ended March 31, 2020 and 2019 was $1.6 and $1.6, respectively. Unrecognized stock-based compensation expense related to outstanding unvested stock options as of March 31, 2020 was $16.4 and is expected to be recognized over a weighted average period of 4.32 years. Any future changes in estimated forfeitures will impact this amount.

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

Any dilutive impact summarized above related to periods when the average market price of our stock exceeded the exercise price of the potentially dilutive stock options then outstanding.

Three-month Period

Summary of Anti-dilutive Options Excluded

Options to purchase shares of common stock

Weighted average exercise prices of options