Stock Compensation - Restricted Stock and Performance Share Grants - Compensation Costs (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock compensation costs	$ 649	$ 760
Executive Officer
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock compensation costs, expensed		(485)
1998 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock compensation costs, expensed	433	437
Stock compensation costs, capitalized	31	131
Stock compensation costs	464	568
NDSI Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock compensation costs, expensed	$ 185	$ 192