Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2016

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Schedule of assumptions used in estimating fair value of stock options using Black-Scholes option pricing model

In determining the estimated fair value of our stock options as of the date of grant, we used the Black-Scholes option pricing model with the following assumptions:

	2016		2015		2014
Risk-free interest rate	0.93 - 1.27%		1.02 - 1.38%		1.3 - 1.4%
Dividend yield	5.50	%	5.00	%	5.00	%
Volatility factors of the expected market price for our common stock	19.1 - 20.6%		19.0 - 20.0%		17.8 - 18.0%
Weighted average expected life of options	4.0 years		4.0 years		4.17 years

Summary of stock option activity

The following is a summary of stock option activity in 2016:

	Shares (000’s)	Weighted Average Exercise Price		Weighted Average Remaining Contractual Life (years)	Intrinsic Value ($000’s)
Outstanding as of December 31, 2015	3,052	$	52.62
Options granted	1,165	62.82
Options exercised	409	49.77
Options forfeited	2	58.84
Options expired	1	46.62
Outstanding as of December 31, 2016	3,805	56.05		7.2	$	30,379
Exercisable as of December 31, 2016	2,629	$	53.23	6.4	$	27,075

Summary of status of nonvested restricted stock and restricted stock units and changes during the year

A summary of the status of our non-vested restricted stock and restricted stock units as of December 31, 2016, and changes during the year ended December 31, 2016 follows:

	Restricted Stock (000’s)	Weighted Average Grant Date Fair Value		Restricted Stock Units (000’s)	Weighted Average Grant Date Fair Value
Nonvested at December 31, 2015	363	$	57.65	14	$	58.02
Granted	181	55.25		13	57.06
Vested	226	56.21		12	56.19
Forfeited	6	58.18		0	0.00
Nonvested at December 31, 2016	312	$	57.29	15	$	58.70