Basis of Presentation (Narratives) (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Basis of Presentation [Line Items]
Expense (income) from deferred compensation plan liability	$ 2,077,000	$ 789,000	$ 1,673,000	$ 3,258,000
Income (loss) from deferred compensation plan assets	$ 2,077,000	$ 789,000	$ 1,673,000	3,258,000
General and Administrative Expense
Basis of Presentation [Line Items]
Unincorporated business tax				$ 1,062,000