Intangible Assets (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Intangible Assets [Abstract]
Amortization expense	$ 35,559	$ 35,124	$ 61,066
Annual amortization expense in 2018	29,448
Annual amortization expense in 2019	20,411
Annual amortization expense in 2020	17,308
Annual amortization expense in 2021	12,859
Annual amortization expense in 2022	$ 7,493