Stockholders' Equity (Tables)

9 Months Ended

Sep. 30, 2018

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:



	2018		2017
First quarter	$	0.37	0.32
Second quarter	0.37		0.32
Third quarter	0.40		0.32
Fourth quarter	0.40		0.32
Total	$	1.54	1.28

Stock Options Granted

The following tables summarize the details of options granted under our stock option plan that were still outstanding as of September 30, 2018, 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		September 30, 2018
Date of Grant	Options Granted	Option Exercise (Strike) Price		Closing Stock Price on Date of Grant		Options Outstanding	Options Exercisable
January 2, 2018	541,786	$	55.00	$	54.54	525,525	21,185
January 3, 2017	764,789	$	47.00	$	46.95	683,528	—
April 19, 2016	845,440	$	46.00	$	45.74	706,116	—
April 21, 2015	893,220	$	42.00	$	41.26	630,784	130,318
April 22, 2014	955,000	$	56.00	$	50.53	519,750	314,000
April 16, 2013	205,000	$	54.00	$	49.25	91,249	57,506
April 17, 2012	1,235,000	$	54.00	$	49.01	828,750	716,250
April 19, 2011	410,000	$	35.00	$	31.78	52,850	40,350
April 20, 2010	530,000	$	30.00	$	27.13	33,150	33,150
Total	6,380,235					4,071,702	1,312,759

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, 2018	2.2	%	5.00	2.3	%	23.45	%	$	10.03
January 3, 2017	1.9	%	5.00	2.6	%	24.49	%	$	8.40
April 19, 2016	1.3	%	5.00	2.6	%	26.34	%	$	8.18
April 21, 2015	1.3	%	5.00	2.7	%	26.84	%	$	7.35
April 22, 2014	1.8	%	5.00	2.0	%	28.55	%	$	9.57
April 16, 2013	0.7	%	5.00	1.6	%	37.42	%	$	12.66
April 17, 2012	0.9	%	5.00	1.4	%	39.25	%	$	13.69
April 19, 2011	2.1	%	5.00	1.6	%	39.33	%	$	11.20
April 20, 2010	2.6	%	5.00	1.5	%	39.10	%	$	8.14

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:



	Nine-month Period		Three-month Period
Reconciliation	2018	2017	2018	2017
Basic weighted average shares outstanding	287,263,379	288,451,470	287,006,910	287,456,943
Weighted shares assumed upon exercise of stock options	195,029	140,104	256,312	121,100
Diluted weighted average shares outstanding	287,458,408	288,591,574	287,263,222	287,578,043

Anti-Dilutive Options Excluded



	Nine-month Period			Three-month Period
Summary of Anti-dilutive Options Excluded	2018		2017	2018		2017
Options to purchase shares of common stock	1,597,342		3,881,605	1,534,795		3,848,126
Weighted average exercise price of options	$	55.02	49.21	$	55.02	49.18