Share-Based Payments - Amounts of compensation expense recognized under stock-based payment programs (Details 1) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock compensation expense	$ 778	$ 160	$ 2,447	$ 2,343
Stock Performance Awards | Executive Officers
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock compensation expense	455	(142)	1,296	915
Restricted Stock Units (RSUs) | Executive Officers
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock compensation expense	64	36	373	416
Restricted Stock Units (RSUs) | Nonexecutive Employees
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock compensation expense	62	86	207	233
Restricted Stock | Executive Officers
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock compensation expense	22	29	73	330
Restricted Stock | Directors
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock compensation expense	128	107	363	311
Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock compensation expense	$ 47	$ 44	$ 135	$ 138