Stockholders' Equity (Tables)

12 Months Ended

Dec. 31, 2016

Stockholders' Equity Note [Abstract]

Stock Option Plan Activity and Stock Options Granted

The following tables summarize the details of options granted under our stock option plan that were still outstanding as of December 31, 2016, and the assumptions used to value those 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		December 31, 2016
Date of Grant	Options Granted	Option Exercise (Strike) Price		Closing Stock Price on Date of Grant		Options Outstanding	Options Exercisable
April 19, 2016	845,440	$	46.00	$	45.74	789,363	—
April 21, 2015	893,220	$	42.00	$	41.26	738,834	—
April 22, 2014	955,000	$	56.00	$	50.53	608,750	122,500
April 16, 2013	205,000	$	54.00	$	49.25	115,000	3,500
April 17, 2012	1,235,000	$	54.00	$	49.01	981,500	682,250
April 19, 2011	410,000	$	35.00	$	31.78	83,900	46,400
April 20, 2010	530,000	$	30.00	$	27.13	147,300	94,800
April 21, 2009	790,000	$	27.00	$	17.61	228,650	186,150
April 15, 2008	550,000	$	27.00	$	24.35	64,650	64,650
Total	6,413,660					3,757,947	1,200,250

A summary of activities under our stock option plan consisted of the following:



	Options Outstanding		Exercise Price⁽¹⁾		Remaining Life⁽²⁾
Outstanding as of January 1, 2016	4,530,982		$	41.49	4.89
Granted	845,440		$	46.00	8.41
Exercised	(1,180,242	)	$	24.80
Cancelled/forfeited	(438,233	)	$	49.49
Outstanding as of December 31, 2016	3,757,947		$	46.81	5.85
Exercisable as of December 31, 2016	1,200,250		$	45.93	3.74



	Options Outstanding		Exercise Price⁽¹⁾		Remaining Life⁽²⁾
Outstanding as of January 1, 2015	4,712,330		$	38.52	4.59
Granted	893,220		$	42.00	8.41
Exercised	(813,838	)	$	23.47
Cancelled/forfeited	(260,730	)	$	45.84
Outstanding as of December 31, 2015	4,530,982		$	41.49	4.89
Exercisable as of December 31, 2015	1,792,242		$	31.00	2.15

⁽¹⁾Weighted average exercise price.

⁽²⁾Weighted average remaining contractual life in years.

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:



Reconciliation	2016	2015	2014
Basic weighted average shares outstanding	288,949,525	291,453,107	296,490,378
Weighted shares assumed upon exercise of stock options	207,998	592,335	822,866
Diluted weighted average shares outstanding	289,157,523	292,045,442	297,313,244

Anti-Dilutive Options Excluded



Summary of Anti-dilutive Options Excluded	2016		2015	2014
Options to purchase shares of common stock	3,095,343		2,611,367	1,903,767
Weighted average exercise prices of options	$	50.09	51.89	54.67