Stock-Based Compensation

3 Months Ended

Mar. 31, 2013

Share-based Compensation [Abstract]

Stock-Based Compensation

Stock-Based Compensation

A summary of restricted stock transactions during the three months ended March 31, 2013 follows:

	Number of shares
Non-vested shares outstanding at January 1, 2013	898,190
Awarded:
Time-vesting (average grant-date fair value of $38.68)	115,557
Performance-based (average grant-date fair value of $36.75)	243,251
Performance-based – achieved 140.83% level (grant-date fair value of $37.91)	93,755
Released:
Time-vesting shares awarded in 2010 through 2012	(144,623	)
Performance-based shares awarded in 2010	(229,624	)
Performance-based awards – achieved 140.83% level	(93,755	)
Non-vested shares outstanding at March 31, 2013	882,751

The average grant-date fair value of restricted stock awarded in 2013 and 2012 was $38.68 and $33.75 for time-vested shares and $36.75 and $39.52 for performance-based shares.

The Company awards shares of restricted stock to certain senior executives annually. The awards consist of time-vesting awards which vest ratably over three years and performance-based shares which cliff vest at the end of three years. The number of performance-based shares that will ultimately vest is based on the level of market performance achieved, ranging between 0% and 200% of the shares originally awarded, and will be settled in stock. The fair value of the performance-based shares awarded was calculated using a Monte Carlo valuation model. The estimated weighted average grant-date fair value of the 243,251 performance-based shares awarded during the first three months of 2013 was $36.75 using a weighted average stock price volatility of 22.4%, an expected term of three years, and a weighed average risk-free interest rate of 0.34%. The variables used to value the 2012 award included a weighted average stock price volatility of 27.80% , an expected term of three years, and a weighted average risk-free rate of 0.40%.

During the first three months of 2013, 93,755 additional performance-based shares were issued under the Company's 2010 award because the Company exceeded the target level (100%) of performance-based shares, established on the original date of the related award, by 40.83%. These shares were issued without restriction.

At March 31, 2013, unrecognized compensation cost related to outstanding restricted stock was $10. The weighted average period over which the expense is expected to be recognized is 2.1 years. The aggregate market value of the shares released and issued on the vesting dates was $18.