Stock-based Awards (Details 2) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Additional disclosures
Stock-based compensation expense	$ 9,453,000	$ 4,144,000
Restricted stock units
Number of Shares
Non-vested at the beginning of period (in shares)	827,997
Granted (in shares)	237,901
Vested (in shares)	(138,145)
Canceled/forfeited (in shares)	(95,991)
Non-vested at the end of the period (in dollars per share)	831,762
Weighted-Average Grant Date Fair Value
Non-vested at the beginning of period (in dollars per share)	$ 12.36
Granted (in dollars per share)	$ 17.73
Vested (in dollars per share)	$ 15.70
Canceled/forfeited (in dollars per share)	$ 10.50
Non-vested at the end of the period (in dollars per share)	$ 13.56
Additional disclosures
Remaining stock-based compensation expense (in dollars)	8,100,000
Weighted-average period for recognition of stock-based compensation expense	3 years 7 months 6 days
Stock-based compensation expense	$ 2,500,000	$ 0