Share-Based Compensation - Components of Share Based Compensation Awards (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Pre-tax compensation expense	$ 475	$ 415	$ 1,285	$ 1,101
Income tax expense (benefit)	(152)	(115)	(386)	(335)
Share-based compensation expense, net of income taxes	323	300	899	766
Stock and ESPP Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Pre-tax compensation expense	89	71	177	197
Income tax expense (benefit)	(17)	(11)	1	(13)
Share-based compensation expense, net of income taxes	72	60	178	184
Restricted Stock Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Pre-tax compensation expense	386	344	1,108	904
Income tax expense (benefit)	(135)	(104)	(387)	(322)
Share-based compensation expense, net of income taxes	$ 251	$ 240	$ 721	$ 582