Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2013

Accounting Policies [Abstract]

Estimated Useful Lives of Assets

The estimated useful lives are as follows:

	Estimated Useful Life
Computer equipment and software	2 to 5 years
Furniture and fixtures	3 to 13 years
Leasehold improvements	Shorter of lease term or estimated useful life of 3 to 5 years

Summary of Weighted Average Assumptions

The fair value of options was estimated at the date of grant using a Black-Scholes option-pricing model with the following weighted-average assumptions:

	Year Ended December 31,
	2013	2012	2011
Risk-free interest rate	1.1%	1.1%	2.5%
Expected dividend yield	0.8—1.1%	0.0—1.3%	—
Expected volatility	58.0%	59.9%	61.9%
Expected term	6.1 years	6.1 years	6.1 years
Weighted-average fair value per share	$10.99	$7.74	$7.76