Employee Stock Benefit Plans (Details 3) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2015		Mar. 31, 2014	Dec. 31, 2014
Additional disclosures
Share-based compensation	5,426		6,074
Restricted stock units
Restricted Stock
Common stock receivable per option exercised (in shares)	1
Vesting percentage	25.00%
Summary of unvested shares of restricted stock, shares
Granted (in shares)	493,000	[1]
Forfeited (in shares)	(2,000)
Outstanding at the end of the period (in shares)	491,000
Summary of unvested shares of restricted stock, weighted-average fair value
Granted (in dollars per share)	15.62	[1]
Forfeited (in dollars per share)	15.62
Outstanding at the end of the period (in dollars per share)	15.62
Options to purchase common stock
Weighted-average assumptions used to estimate the fair value of the stock options using the Black-Scholes option-pricing model
Expected volatility (as a percent)	46.00%		46.60%
Expected term	6 years		6 years 1 month 6 days
Risk-free interest rate (as a percent)	1.70%		1.80%
Additional disclosures
Shares issuable under outstanding options	21,090,000			19,957,000

[1] RSUs granted in the three months ended March 31, 2015 primarily represent awards made in connection with the Company’s annual equity grants in March 2015.