Operating Expenses (Schedule of Depreciation and Amortization Expenses) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Operating Expenses [Abstract]
Depreciation expense	$ 6,916	$ 6,792
Amortization expense	9,275	3,546
Total depreciation and amortization expenses	$ 16,191	$ 10,338