Stockholders' Equity (Tables)

12 Months Ended

Dec. 31, 2015

Stockholders' Equity Note [Abstract]

Authorized, Issued and Outstanding Shares

Our authorized, issued, and outstanding shares (stated in whole numbers) at year end consisted of the following:

	Par Value	2015	2014
Preferred stock	$0.01/share
Shares authorized		5,000,000	5,000,000
Shares issued and outstanding		—	—
Common stock	$0.01/share
Shares authorized		400,000,000	400,000,000
Shares issued and outstanding		289,581,682	295,867,844

Stock Option Plan Activity and 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		December 31, 2015
Date of Grant						Options Outstanding	Options Exercisable
April 21, 2015	893,220	$	42.00	$	41.26	817,990	—
April 22, 2014	955,000	$	56.00	$	50.53	797,500	5,000
April 16, 2013	205,000	$	54.00	$	49.25	125,000	2,500
April 17, 2012	1,235,000	$	54.00	$	49.01	1,039,500	341,250
April 19, 2011	410,000	$	35.00	$	31.78	250,300	150,300
April 20, 2010	530,000	$	30.00	$	27.13	210,350	120,350
April 21, 2009	790,000	$	27.00	$	17.61	293,100	200,600
April 15, 2008	550,000	$	27.00	$	24.35	147,750	122,750
April 17, 2007	4,380,000	$	22.50	$	20.15	849,492	849,492
Total	9,948,220					4,530,982	1,792,242

A summary of the activity under our stock option plan is as follows:

	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

	Options Outstanding		Exercise Price(1)		Remaining Life(2)
Outstanding as of January 1, 2014	4,356,630		$	34.06	4.66
Granted	955,000		$	56.00	8.41
Exercised	(314,300	)	$	24.49
Cancelled/forfeited	(285,000	)	$	44.39
Outstanding as of December 31, 2014	4,712,330		$	38.52	4.59
Exercisable as of December 31, 2014	1,972,330		$	27.89	2.51

⁽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 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
April 17, 2007	4.6	%	4.85	1.0	%	31.59	%	$	5.63

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	2015	2014	2013
Basic weighted average shares outstanding	291,453,107	296,490,378	296,754,160
Weighted shares assumed upon exercise of stock options	592,335	822,866	929,428
Diluted weighted average shares outstanding	292,045,442	297,313,244	297,683,588

Anti-Dilutive Options Excluded

Summary of Anti-dilutive Options Excluded	2015		2014	2013
Options to purchase shares of common stock	2,611,367		1,903,767	1,273,527
Weighted average exercise prices of options	$	51.89	54.67	54.00