Fair-Value Measurements (Schedule of Fair Value of Financial Assets and Liabilities) (Details) - USD ($) $ in Thousands		Jun. 30, 2020		Dec. 31, 2019
Derivative Asset [Abstract]
Equity securities, fv-ni, cost		$ 500		$ 500
Fair Value, Inputs, Level 1 [Member] | Fair Value, Recurring [Member]
Assets, Fair Value Disclosure [Abstract]
Cash equivalents		21,322		16,375
Common stock of unaffiliated foreign public company	[1]	708		839
Interest rate swaps		0		0
Liabilities, Fair Value Disclosure [Abstract]
Interest rate swaps		0		0
Fair Value, Inputs, Level 2 [Member] | Fair Value, Recurring [Member]
Assets, Fair Value Disclosure [Abstract]
Cash equivalents		0		0
Common stock of unaffiliated foreign public company	[1]	0		0
Interest rate swaps		0		0
Liabilities, Fair Value Disclosure [Abstract]
Interest rate swaps		(15,701)	[2]	(5,518)	[3]
Interest Rate Swap [Member]
Derivative Liability [Abstract]
Derivative Liability, Fair Value, Gross Asset		1,700		15,200
Liability for fixed rate leg		$ 17,400		$ 20,700

[1] Original cost basis $0.5 million.

[2] Net of $1.7 million receivable floating leg and $17.4 million liability fixed leg.

[3] Net of $15.2 million receivable floating leg and $20.7 million liability fixed leg.