Equity-Based Compensation (Details of Equity-Based Compensation Expense and Related Income Tax Benefit) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee equity-based compensation expense	$ 3,094	$ 1,157
Accelerated share-based termination benefits in connection with the merger	1,678
Deferred compensation stock equivalent units expense	185	161
Total tax benefit recognized for share-based expense	111	93
Performance shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee equity-based compensation expense	936	868
Restricted stock units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee equity-based compensation expense	$ 480	$ 289