Stock Incentive Plans (Summary of Restricted Common Stock and Performance-Based Restricted Stock Unit Activity) (Details)	9 Months Ended
	Sep. 30, 2015 $ / shares shares
Restricted Common Stock
Number of Shares
Unvested at the beginning of the period (in shares)	752,701
Granted (in shares)	429,752
Vested (in shares)	(39,000)
Forfeited (in shares)	(63,716)
Unvested at the end of the period (in shares)	1,079,737
Weighted Average Grant Date Fair Value
Unvested at the beginning of the period (in dollars per share) | $ / shares	$ 11.90
Granted (in dollars per share) | $ / shares	13.05
Vested (in dollars per share) | $ / shares	(9.84)
Forfeited (in dollars per share) | $ / shares	(11.73)
Unvested at the end of the period (in dollars per share) | $ / shares	$ 12.44
Restricted Stock Units
Number of Shares
Unvested at the beginning of the period (in shares)	776,500
Granted (in shares)	409,800
Forfeited (in shares)	(65,800)
Unvested at the end of the period (in shares)	1,120,500
Weighted Average Grant Date Fair Value
Unvested at the beginning of the period (in dollars per share) | $ / shares	$ 10.66
Granted (in dollars per share) | $ / shares	12.64
Forfeited (in dollars per share) | $ / shares	(10.98)
Unvested at the end of the period (in dollars per share) | $ / shares	$ 11.37