Common Stock (Tables)

12 Months Ended

Dec. 31, 2016

The following summarizes options activity:


	Years Ended December 31,
	2016					2015					2014
	Number			Average		Number			Average		Number			Average
	of			Exercise		of			Exercise		of			Exercise
	Shares			Price		Shares			Price		Shares			Price
Shares under option at beginning of year		15,430,307		$	59.50		10,881,133		$	61.22		11,535,566		$	58.36
Granted		3,672,411			28.26		5,746,153			54.74		3,389,547			69.00
Spun-off		—			—		—			—		(1,567,348	)		70.56
Cancelled		(1,517,065	)		49.95		(886,356	)		62.73		(498,967	)		70.32
Exercised		(146,593	)		28.53		(310,623	)		22.56		(1,977,665	)		53.56

Shares under option at end of year		17,439,060		$	54.08		15,430,307		$	59.50		10,881,133		$	61.22

Exercisable at end of year		9,828,897		$	61.56		7,498,414		$	60.30		5,903,712		$	55.06

Summary of Stock Option Outstanding Information

The following summarizes information about stock options outstanding at December 31, 2016:


	Weighted-Avg		Options Outstanding				Options Exercisable
	Remaining				Weighted-Avg				Weighted-Avg
Range of Exercise Price	Contractual Life		Shares		Exercise Price		Shares		Exercise Price
$12.15 - $55.00		7.56		10,108,458	$	42.77		3,312,182	$	45.43
$55.01 - $70.00		6.21		4,720,781		66.21		3,906,894		65.63
$70.01 - $77.99		4.66		2,609,821		75.95		2,609,821		75.95

Total		6.76		17,439,060	$	54.08		9,828,897	$	61.56

Assumption Used in Determination of Fair Value of Share Based Payment Awards

The use of the Black Scholes model requires the use of actual employee exercise activity data and the use of a number of complex assumptions including expected volatility, risk-free interest rate, expected dividends and expected term.


	Years Ended December 31,
	2016			2015			2014
Valuation Assumptions:
Expected volatility		48.6	%		49.1	%		49.4	%
Risk-free interest rate		1.2	%		1.5	%		1.5	%
Expected dividends	$	6.52		$	3.36		$	1.39
Expected term (in years)		3.0			3.0			3.7

Summary of Information and Changes in Stock Options with Regard to Stock Option Plans

The following summary presents information regarding outstanding options at December 31, 2016 and changes during 2016 with regard to options under all stock option plans:


						Weighted
				Weighted- Average		Remaining Contractual
	Shares			Exercise Price		Term (years)		Aggregate Intrinsic Value
Outstanding at December 31, 2015		15,430,307		$	59.50		5.16	$	5,894,977
Granted		3,672,411		$	28.26
Cancelled		(1,517,065	)	$	49.95
Exercised		(146,593	)	$	28.53

Outstanding at December 31, 2016		17,439,060		$	54.08		6.76	$	37,928,494

Vested or expected to vest		17,212,352		$	54.08		6.76	$	37,408,874

Exercisable at December 31, 2016		9,828,897		$	61.56		5.42	$	6,700,856

Summary of Information Regarding Outstanding SARs

The following summary presents information regarding outstanding SARs at December 31, 2016 and changes during 2016 with regard to SARs:


	Year Ended December 31,
	2016
	Number			Average
	of			Exercise
	Shares			Price
Shares under SARs at beginning of year		—		$	—
Granted		4,618,400			28.32
Cancelled		(276,660	)		28.24

Shares under SARs at end of year		4,341,740		$	28.32

Exercisable at end of year		—		$	—

Summary of Information Regarding Outstanding Restricted Shares

The following summary presents information regarding outstanding restricted shares:


	Years Ended December 31,
	2016					2015					2014
				Weighted-					Weighted-					Weighted-
	Number			Average		Number			Average		Number			Average
	of			Grant Date		of			Grant Date		of			Grant Date
	Units			Fair Value		Units			Fair Value		Units			Fair Value
Nonvested at beginning of year		1,969,250		$	61.53		1,569,141		$	73.73		1,643,193		$	67.98
Granted		3,384,325			31.59		954,075			53.27		708,821			70.14
Spin-off		—			—		—			—		(319,949	)		70.56
Vested		(565,202	)		29.32		(405,327	)		54.30		(348,981	)		74.97
Cancelled		(224,390	)		49.95		(148,639	)		62.73		(113,943	)		70.32

Nonvested at end of year		4,563,983		$	41.10		1,969,250		$	61.53		1,569,141		$	73.73