Share-Based Compensation (Summary of Grant Date Fair Value of Awards) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Grant date fair value of awards during the period:
Options	$ 19,944	$ 12,527
Restricted stock	3,708	2,114
Total	23,652	14,641
Share-based compensation expense:
Options	1,225	758
Restricted stock	805	966
Total	2,030	1,724
Income tax benefit/(deficiency) related to share-based compensation [Abstract]
Options	243	301
Restricted stock	151	162
Total	$ 394	$ 463