Commitments And Contingencies (Future Minimum Payments Under Operating Leases) (Details) $ in Thousands	Dec. 31, 2017 USD ($)
Commitments and Contingencies Disclosure [Abstract]
Operating Leases, Future Minimum Payments Receivable, Current	$ 129,019
Total Minimum Payments, 2018	53,369
Total Minimum Payments, 2019	52,929
Total Minimum Payments, 2020	51,102
Total Minimum Payments, 2021	47,482
Total Minimum Payments, 2022	37,320
Total Minimum Payments, Years subsequent to 2022	59,238
Non-cancelable Subleases, 2018	21,109
Non-cancelable Subleases, 2019	20,664
Non-cancelable Subleases, 2020	18,756
Non-cancelable Subleases, 2021	15,212
Non-cancelable Subleases, 2022	8,724
Non-cancelable Subleases, Years subsequent to 2022	8,868
Net Minimum Payments, 2018	32,260
Net Minimum Payments, 2019	32,265
Net Minimum Payments, 2020	32,346
Net Minimum Payments, 2021	32,270
Net Minimum Payments, 2022	28,596
Net Minimum Payments, Years subsequent to 2022	50,370
Operating Leases, Future Minimum Payments Receivable, in Two Years	118,287
Operating Leases, Future Minimum Payments Receivable, in Three Years	83,123
Operating Leases, Future Minimum Payments Receivable, in Four Years	56,799
Operating Leases, Future Minimum Payments Receivable, in Five Years	17,930
Operating Leases, Future Minimum Payments Receivable, Thereafter	$ 20,310