Employee Benefits and Share-Based Compensation - Restricted Stock Activity (Details) - 2009 Plan [Member] - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	9 Months Ended		12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Restricted Stock Units (RSUs) [Member]
Number of Shares
Outstanding at December 31, 2014 (in shares)	399
Granted (in shares)	131
Vested (in shares)	(99)
Forfeited (in shares)	(29)
Outstanding and unvested at September 30, 2015 (in shares)	402		399
Expected to vest at September 30, 2015 (in shares)	392
Weighted-Average Grant Date Fair Value
Outstanding and unvested (in dollars per share)	$ 24.00
Granted (in dollars per share)	34.72	$ 25.16
Vested (in dollars per share)	21.51
Forfeited (in dollars per share)	23.79
Outstanding and unvested (in dollars per share)	$ 28.10		$ 24.00
Weighted-average remaining years, expected to vest at September 30, 2015 (in years)	1 year 2 months 12 days
Weighted-average remaining years, outstanding and unvested (in years)	1 year 3 months 18 days		1 year 6 months
Aggregate Intrinsic Value
Outstanding and unvested at September 30, 2015	$ 12,503
Expected to vest after September 30, 2015	12,181
Unrecognized compensation expense	$ 9,300
Weighted average period of compensation cost recognized	2 years 4 months 24 days
Restricted Stock Awards [Member]
Number of Shares
Outstanding at December 31, 2014 (in shares)	36
Granted (in shares)	37
Vested (in shares)	(41)
Forfeited (in shares)	(1)
Outstanding and unvested at September 30, 2015 (in shares)	31		36
Weighted-Average Grant Date Fair Value
Outstanding and unvested (in dollars per share)	$ 26.47
Granted (in dollars per share)	36.05
Vested (in dollars per share)	26.47
Forfeited (in dollars per share)	27.65
Outstanding and unvested (in dollars per share)	$ 35.95		$ 26.47
Aggregate Intrinsic Value
Unrecognized compensation expense	$ 700
Weighted average period of compensation cost recognized	8 months 24 days