Share-Based Compensation - Summary of Share-Based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Summary of share-based compensation expense
Share-based compensation before income tax benefit	$ 8,038	$ 3,848	$ 2,930
Income tax benefit	(2,988)	(1,454)	(1,102)
Share-based compensation, net of income tax benefit	5,050	2,394	1,828
Performance unit incentive plan (“PUP”)
Summary of share-based compensation expense
Share-based compensation before income tax benefit	5,703	1,692	359
Restricted stock
Summary of share-based compensation expense
Share-based compensation before income tax benefit	2,073	2,111	2,495
Restricted stock units
Summary of share-based compensation expense
Share-based compensation before income tax benefit	$ 262	$ 45	$ 76