Fair Value Disclosure (On a Recurring Basis) (Details) - Fair value measurements, recurring - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Level 1
Assets:
Equity securities	$ 9,086	$ 9,166
Interest rate swap agreements	0	0
Assets at fair value	9,086	9,166
Level 2
Assets:
Equity securities	0	0
Interest rate swap agreements	41	42
Assets at fair value	41	42
Level 3
Assets:
Equity securities	0	0
Interest rate swap agreements	0	0
Assets at fair value	0	0
Total
Assets:
Equity securities	9,086	9,166
Interest rate swap agreements	41	42
Assets at fair value	$ 9,127	$ 9,208