Stockholders' Equity (Tables)

6 Months Ended

Jun. 30, 2016

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:

	2016		2015
First quarter	$	0.30	0.28
Second quarter	0.30		0.28
Third quarter	0.30		0.28
Fourth quarter			0.28
Total	$	0.90	1.12

Stock Options Granted

The following tables summarize the details of grants made under our stock option plan that are still outstanding, and the assumptions used to value these grants. All options granted 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, 2016
Date of Grant						Options Outstanding	Options Exercisable
April 19, 2016	845,440	$	46.00	$	45.74	819,466	—
April 21, 2015	893,220	$	42.00	$	41.26	775,020	—
April 22, 2014	955,000	$	56.00	$	50.53	642,500	10,000
April 16, 2013	205,000	$	54.00	$	49.25	115,000	2,500
April 17, 2012	1,235,000	$	54.00	$	49.01	1,015,250	617,500
April 19, 2011	410,000	$	35.00	$	31.78	200,800	163,300
April 20, 2010	530,000	$	30.00	$	27.13	181,725	121,725
April 21, 2009	790,000	$	27.00	$	17.61	252,650	208,900
April 15, 2008	550,000	$	27.00	$	24.35	114,100	114,100
Total	6,413,660					4,116,511	1,238,025

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
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
April 15, 2008	2.7	%	5.00	1.0	%	30.93	%	$	7.75

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 calculation because they were anti-dilutive:

	Six-month Period		Three-month Period
Reconciliation	2016	2015	2016	2015
Basic weighted average shares outstanding	288,863,482	293,191,566	288,918,945	291,176,985
Weighted shares assumed upon exercise of stock options	268,820	678,586	200,525	653,152
Diluted weighted average shares outstanding	289,132,302	293,870,152	289,119,470	291,830,137

Anti-Dilutive Options Excluded

	Six-month Period				Three-month Period
Summary of Anti-dilutive Options Excluded	2016		2015		2016		2015
Options to purchase shares of common stock	2,941,864		2,395,247		3,253,343		2,724,639
Weighted average exercise price of options	$	50.39	$	52.97	$	49.91	$	51.56