Share-Based Compensation (Notes)
 9 Months Ended
Sep. 30, 2016
Share-based Compensation [Abstract]  
Disclosure of Compensation Related Costs, Share-based Payments
Share-Based Compensation
Stock Benefit Plans
We maintain benefit plans whereby shares of our common stock may be issued pursuant to the exercise of stock options, restricted stock, or other stock-based awards granted to officers and key employees. In May 2016, our shareholders approved the 2016 Equity Incentive Plan that reserves 13,000,000 shares of common stock for outstanding and future awards of stock options, restricted stock, and other stock-based awards to officers and key employees.
We utilize the Black-Scholes option valuation model for estimating the fair value of our stock options. This model uses a range of assumptions related to volatility, the risk-free interest rate, the expected life, and the dividend yield. The fair values of our stock options are calculated using the following weighted average assumptions for the nine months ended September 30, 2016:
Dividend yield
2.0
%
Expected volatility
19.7
%
Risk-free interest rate
1.0
%
Expected holding period (in years)
4.0


Stock Options
The following table sets forth stock option activity for the nine months ended September 30, 2016:
 
Options
 
Weighted Average
Exercise Price
Outstanding at December 31, 2015
11,047,920

 
$
13.98

Granted
1,863,700

 
$
22.28

Exercised
(1,924,324
)
 
$
8.33

Canceled
(28,272
)
 
$
20.98

Outstanding at September 30, 2016
10,959,024

 
$
16.36

Exercisable at September 30, 2016
7,100,945

 
$
13.54


As of September 30, 2016, the unrecognized compensation expense related to stock options of $10.3 million is expected to be recognized over a weighted average period of 1.3 years.
Restricted Stock Awards
Restricted stock awards activity for the nine months ended September 30, 2016 was as follows:
 
Restricted
Stock Awards
 
Weighted Average
Grant Date
Fair Value
Nonvested restricted stock awards at December 31, 2015
573,739

 
$
19.32

Granted
241,510

 
$
22.28

Vested
(313,247
)
 
$
18.14

Forfeited
(1,258
)
 
$
20.85

Nonvested restricted stock awards at September 30, 2016
500,744

 
$
21.48


As of September 30, 2016, the unrecognized compensation expense related to restricted stock awards of $7.1 million is expected to be recognized over a weighted average period of 1.8 years.
Restricted Stock Units
Restricted stock units activity for the nine months ended September 30, 2016 was as follows:
 
Restricted
Stock Units
 
Weighted Average
Grant Date
Fair Value
Nonvested restricted stock units at December 31, 2015
—

 
$
—

Granted
130,660

 
$
25.72

Forfeited
(5,200
)
 
$
25.72

Nonvested restricted stock units at September 30, 2016
125,460

 
$
25.72


As of September 30, 2016, the unrecognized compensation expense related to restricted stock units of $2.7 million is expected to be recognized over a weighted average period of 2.3 years.