Fair-Value Measurements (Schedule of Fair Value of Financial Assets and Liabilities) (Details) - USD ($) $ in Thousands		Mar. 31, 2019		Dec. 31, 2018
Derivative asset:
Common stock of foreign public company, original cost		$ 500		$ 500
Interest Rate Current Swap [Member]
Derivative asset:
Liability for fixed rate leg		26,700		32,000
Receivable for floating rate leg		25,900		27,500
Quoted Prices in Active Markets (Level 1) [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Cash equivalents		13,897		14,234
Common stock of unaffiliated foreign public company	[1]	743		731
Liabilities:
Interest rate swaps
Significant Other Observable Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Cash equivalents
Common stock of unaffiliated foreign public company	[1]
Liabilities:
Interest rate swaps		$ 822	[2]	$ 4,548	[3]

[1] Original cost basis $0.5 million.

[2] Net of $26.7 million receivable floating leg and $25.9 million liability fixed leg.

[3] Net of $32.0 million receivable floating leg and $27.5 million liability fixed leg.