Basis of Presentation (Narratives) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Basis of Presentation [Line Items]
Expense (income) from deferred compensation plan liability	$ 1,861	$ 1,975	$ 3,534	$ 5,233
Income (loss) from deferred compensation plan assets	$ 1,861	$ 1,975	$ 3,534	5,233
General and Administrative Expense
Basis of Presentation [Line Items]
Unincorporated business tax				$ 1,062