Stock-Based Compensation - Allocation of Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	$ 637	$ 1,986	$ 6,096	$ 3,731
Restricted stock awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	415	1,202	2,354	2,202
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	46	41	616	72
Performance share units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	157	743	2,590	1,457
Stock appreciation rights
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	$ 19	$ 0	$ 536	$ 0