This item represents the cost of debt securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

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Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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Marketable Investments (Details 2) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
Marketable Investments (Details 2) - USD ($) $ in Thousands	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Available for Sale Securities:
Amortized Cost	$ 581		$ 600
Gross Unrealized Gains
Gross Unrealized Loss		(87)
Fair Value	581		600
Gain on sale of marketable securities		243
Unrealized net loss on equity securities	(124)
Corporate Debt Securities [Member]
Available for Sale Securities:
Amortized Cost	581		600
Gross Unrealized Gains
Gross Unrealized Loss
Fair Value	$ 581		$ 600