Leases (Narrative) (Details) - USD ($)	Jun. 30, 2020	Dec. 31, 2019
Lessee, Lease, Description [Line Items]
Weighted average remaining lease term	15 years 6 months
Discount rate	4.10%
Weighted average remaining finance lease term	3 years 4 months 24 days
Finance discount rate	3.80%
Future minimum sublease payments	$ 359,000
Net book value	$ 475,936,000	$ 484,482,000
Minimum [Member]
Lessee, Lease, Description [Line Items]
Operating lease fixed term	1 month
Finance lease term	1 month
Maximum [Member]
Lessee, Lease, Description [Line Items]
Operating lease fixed term	20 years
Finance lease term	6 years
Finance leases [Member]
Lessee, Lease, Description [Line Items]
Net book value	$ 24,461,000	$ 23,258,000