Operating Expenses (Schedule of Depreciation and Amortization Expenses) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Operating Expenses [Abstract]
Depreciation expense	$ 7,168	$ 6,916
Amortization expense	9,947	9,275
Total depreciation and amortization expenses	$ 17,115	$ 16,191