Share-Based Compensation - Summary of Share-Based Compensation Expenses (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Summary of share-based compensation expense
Share-based compensation before income tax benefit	$ 59	$ 1,202	$ 1,562	$ 3,569
Income tax benefit	(17)	(445)	(587)	(1,326)
Total share-based compensation, net of income tax benefit	42	757	975	2,243
Restricted stock/performance-based restricted stock (PBRS)
Summary of share-based compensation expense
Share-based compensation before income tax benefit	653	802	2,066	2,522
Performance unit incentive plan (PUP)
Summary of share-based compensation expense
Share-based compensation before income tax benefit	(600)	347	(505)	871
Restricted Stock Units and Performance Based Restricted Stock Units
Summary of share-based compensation expense
Share-based compensation before income tax benefit	6	3	1	104
Stock options
Summary of share-based compensation expense
Share-based compensation before income tax benefit	$ 0	$ 50	$ 0	$ 72