Employee Benefits and Share-Based Compensation - Restricted Stock Activity (Details) - 2009 Plan [Member] - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	6 Months Ended		12 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Restricted Stock Units (RSUs) [Member]
Number of Shares
Outstanding at December 31, 2014 (in shares)	399
Granted (in shares)	65
Vested (in shares)	(77)
Forfeited (in shares)	(23)
Outstanding and unvested at June 30, 2015 (in shares)	364		399
Expected to vest at June 30, 2015 (in shares)	353
Weighted-Average Grant Date Fair Value
Outstanding and unvested (in dollars per share)	$ 24.00
Granted (in dollars per share)	34.19	$ 26.46
Vested (in dollars per share)	21.57
Forfeited (in dollars per share)	22.35
Outstanding and unvested (in dollars per share)	$ 26.45		$ 24.00
Weighted-average remaining years, expected to vest at June 30, 2015 (in years)	1 year 3 months 18 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 June 30, 2015	$ 13,714
Expected to vest at June 30, 2015	13,329
Unrecognized compensation expense	$ 8,400
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 June 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	$ 1,000
Weighted average period of compensation cost recognized	10 months 24 days