Stock-Based Compensation

6 Months Ended

Jun. 30, 2012

Share-based Compensation [Abstract]

Stock-Based Compensation

Stock-Based Compensation

A summary of restricted stock transactions during the six months ended June 30, 2012 follows:

	Number of shares
Non-vested shares outstanding at January 1, 2012	997,497
Awarded:
Time-vesting (average grant-date fair value of $33.75)	126,582
Performance-based (average grant-date fair value of $39.52)	216,188
Performance-based – achieved 149% level (grant-date fair value of $33.98)	125,552
Released:
Time-vesting shares awarded in 2009 through 2011	(185,848	)
Performance-based shares awarded in 2009	(256,229	)
Performance-based awards – achieved 149% level	(125,552	)
Non-vested shares outstanding at June 30, 2012	898,190

Annually the Company awards shares of restricted stock to certain senior executives. 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 216,188 performance-based shares awarded during the first six months of 2012 was $39.52 using a weighted average stock price volatility of 27.8%, an expected term of three years, and a weighed average risk-free interest rate of 0.36%.

During the first six months of 2012, 125,552 additional performance-based shares were issued under the Company's 2009 award because the Company exceeded the target level (100%) of performance-based shares, established on the original date of the related award, by 49%. These shares were issued without restriction.

At June 30, 2012, unrecognized compensation cost related to outstanding restricted stock was $9. The weighted average period over which the expense is expected to be recognized is 1.7 years. The aggregate market value of the shares released and issued on the vesting dates was $19.