Equity-Based Compensation Expense (Tables)

6 Months Ended

Jun. 30, 2013

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Black-Scholes Option-Pricing Model Assumptions

The fair value of the Options granted during the six months ended June 30, 2013 was estimated on the grant date using the Black-Scholes option-pricing model based on the following assumptions:

Estimated average option life (years)	5.29
Risk free interest rate (range)	0.42% - 1.42%
Expected volatility (range)	17.98% - 32.72%
Expected dividend rate	0.00%
Grant-date fair value per share of options granted	$278.41