Operating Expenses (Schedule of Depreciation and Amortization Expenses) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Operating Expenses [Abstract]
Depreciation expense	$ 7,252	$ 7,228	$ 21,460	$ 20,813
Amortization expense	9,471	7,609	27,991	16,234
Total depreciation and amortization expenses	$ 16,723	$ 14,837	$ 49,451	$ 37,047