Share-Based Compensation - Summary of Share-Based Compensation Expenses (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Summary of share-based compensation expense
Share-based compensation before income tax benefit	$ 3,848	$ 2,930	$ 5,221
Income tax benefit	(1,454)	(1,102)	(1,936)
Share-based compensation, net of income tax benefit	2,394	1,828	3,285
Restricted Stock
Summary of share-based compensation expense
Share-based compensation before income tax benefit	2,111	2,495	3,073
Performance unit incentive plan (“PUP”)
Summary of share-based compensation expense
Share-based compensation before income tax benefit	1,692	359	1,864
Restricted stock units
Summary of share-based compensation expense
Share-based compensation before income tax benefit	45	76	177
Stock Options
Summary of share-based compensation expense
Share-based compensation before income tax benefit	$ 0	$ 0	$ 107