Equity-Based Compensation (Details of Equity-Based Compensation Expense and Related Income Tax Benefit) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee equity-based compensation expense	$ 1,614	$ 1,191	$ 4,708	$ 2,348
Accelerated share-based termination benefits in connection with the merger	86		1,764
Deferred compensation stock equivalent units expense	53	161	181	322
Total tax benefit recognized for share-based expense	73	96	184	189
Performance shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee equity-based compensation expense	1,074	905	2,010	1,773
Restricted stock units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee equity-based compensation expense	$ 454	$ 286	$ 934	$ 575