Operating Expenses (Schedule of Depreciation and Amortization Expenses) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Operating Expenses
Depreciation expense	$ 29,112	$ 29,021	$ 28,337
Amortization expense	41,389	37,593	24,357
Total depreciation and amortization expenses	$ 70,501	$ 66,614	$ 52,694