Share-Based Compensation and Benefit Plans (Other Share-Based Compensation Activity) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Employee stock purchase plan [Member]
Share-Based Compensation and Benefit Plans
Compensation expense for share-based compensation	$ 622	$ 569	$ 1,831	$ 1,689
Income tax benefit from compensation expense for share-based compensation	155	141	456	418
Restricted stock [Member]
Share-Based Compensation and Benefit Plans
Compensation expense for share-based compensation	351	339	1,038	1,031
Income tax benefit from compensation expense for share-based compensation	$ 87	$ 84	$ 258	$ 255