Common Stock (Tables)

6 Months Ended

Jun. 30, 2015

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

Assumptions Used for Calculating Fair Values of Stock Option Awards

The fair value of share-based awards is determined at the time the awards are granted which is generally in January of each year, and requires judgment in estimating employee and market behavior. There were no stock options granted in 2015.

	Six Months Ended June 30,
	2015			2014
Stock Options Granted
Weighted average grant date fair value, per share	$	—		$	26.46
Weighted average assumptions used:
Expected volatility	—		%	52.8		%
Expected lives				5.0
Risk-free interest rates	—		%	1.7		%
Dividend yields	—		%	—		%

Stock Options Status and Activity

Stock Options — The following table reflects the status and activity for all options to purchase common stock for the period indicated:

	Six Months Ended June 30, 2015
	Shares Under Option		Weighted Avg. Exercise Prices		Weighted Avg. Remaining Life in Years	Aggregate Intrinsic Value
						(Millions)
Outstanding Stock Options
Outstanding, January 1, 2015	1,454,003		$	31.16	4.4	$	33
Canceled	(20,427	)	23.75
Exercised	(96,997	)	20.78			3
Outstanding, March 31, 2015	1,336,579		$	32.03	4.3	$	31
Forfeited	(7,531	)	47.36
Exercised	(141,644	)	14.68			6
Outstanding, June 30, 2015	1,187,404		$	34.00	4.2	$	30

Nonvested Restricted Shares

Restricted Stock — The following table reflects the status for all nonvested restricted shares for the period indicated:

	Six Months Ended June 30, 2015
	Shares		Weighted Avg. Grant Date Fair Value
Nonvested Restricted Shares
Nonvested balance at January 1, 2015	286,051		$	42.35
Granted	350,101		53.40
Vested	(150,171	)	37.86
Nonvested balance at March 31, 2015	485,981		$	51.70
Granted	17,164		56.06
Vested	(13,008	)	46.37
Forfeited	(11,034	)	48.85
Nonvested balance at June 30, 2015	479,103		$	52.07