Leases (Supplemental Information Relating to Operating Leases) (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Jan. 01, 2019
Leases [Abstract]
Lease expense incurred: Operating lease cost	$ 9,355
Operating lease right of use assets	53,690	$ 60,325
Operating lease liabilities	59,335	$ 66,551
Operating cash flows from operating leases	$ 8,617
Weighted average remaining operating lease term	5 years 10 months 24 days
Weighted average discount rate on operating leases	4.48%