Stockholders' Equity (Tables)

6 Months Ended

Jun. 30, 2017

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:

	2017		2016
First quarter	$	0.32	0.30
Second quarter	0.32		0.30
Third quarter	0.32		0.30
Fourth quarter			0.30
Total	$	0.96	1.20

Stock Options Granted

The following tables summarize the details of options granted under our stock option plan that were still outstanding as of June 30, 2017, 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		June 30, 2017
Date of Grant						Options Outstanding	Options Exercisable
January 3, 2017	764,789	$	47.00	$	46.95	747,772	—
April 19, 2016	845,440	$	46.00	$	45.74	771,432	—
April 21, 2015	893,220	$	42.00	$	41.26	712,290	—
April 22, 2014	955,000	$	56.00	$	50.53	582,500	116,250
April 16, 2013	205,000	$	54.00	$	49.25	110,000	57,250
April 17, 2012	1,235,000	$	54.00	$	49.01	965,125	778,603
April 19, 2011	410,000	$	35.00	$	31.78	73,800	48,800
April 20, 2010	530,000	$	30.00	$	27.13	110,300	84,050
April 21, 2009	790,000	$	27.00	$	17.61	224,150	224,150
Total	6,628,449					4,297,369	1,309,103

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 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
April 21, 2009	1.9	%	5.00	1.0	%	38.80	%	$	3.64

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:

	Six-month Period		Three-month Period
Reconciliation	2017	2016	2017	2016
Basic weighted average shares outstanding	288,948,734	288,863,482	288,655,020	288,918,945
Weighted shares assumed upon exercise of stock options	150,582	268,820	133,943	200,525
Diluted weighted average shares outstanding	289,099,316	289,132,302	288,788,963	289,119,470

Anti-Dilutive Options Excluded

	Six-month Period			Three-month Period
Summary of Anti-dilutive Options Excluded	2017		2016	2017		2016
Options to purchase shares of common stock	3,603,850		2,941,864	3,897,177		3,253,343
Weighted average exercise price of options	$	49.81	50.39	$	49.18	49.91