Leases (Lease Costs and Supplemental Cash Flow Information Related to Leases) (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019 USD ($)
Leases [Abstract]
Operating lease costs	$ 3,961
Short-term lease costs (1)	880	[1]
Total lease costs	4,841
Cash paid for operating leases included in the measurement of lease liabilities	3,945
ROU assets obtained in exchange for lease liabilities	$ 69,562

[1] Includes variable lease costs which are immaterial.