Share-Based Compensation - Summary of Share-Based Compensation Expenses (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Summary of share-based compensation expense
Share-based compensation before income tax benefit	$ 1,025	$ 59	$ 3,131	$ 1,562
Income tax benefit	(381)	(17)	(1,180)	(587)
Share-based compensation, net of income tax benefit	644	42	1,951	975
Restricted stock
Summary of share-based compensation expense
Share-based compensation before income tax benefit	523	653	1,623	2,066
Performance unit incentive plan (“PUP”)
Summary of share-based compensation expense
Share-based compensation before income tax benefit	456	(600)	1,444	(505)
Restricted stock units
Summary of share-based compensation expense
Share-based compensation before income tax benefit	$ 46	$ 6	$ 64	$ 1