Leased Assets and Liabilities (Lease Expense) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Leases [Abstract]
Operating lease expense	$ 12,347	$ 12,395	$ 34,750	$ 33,835
Amortization of leased assets	838	692	2,529	1,934
Interest on lease liabilities	172	135	520	378
Variable lease expense	4,969	4,272	18,821	16,486
Sublease income	(381)	(680)	(1,726)	(1,132)
Total expense	$ 17,945	$ 16,814	$ 54,894	$ 51,501