Investments (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Schedule of Available-for-sale Securities
Debt securities, Cost	$ 4,304	$ 4,306
Debt securities, Carrying Value	4,376	4,382
Total, Cost	13,397	14,706
Total, Gross Unrealized Gains	9,511	10,409
Total, Gross Unrealized Losses	(55)	(44)
Total, Carrying Value	22,853	25,071
Available-for-sale Securities, Debt Maturities [Abstract]
Due in one year or less, Amortized Cost	193	182
Due after one year through five years, Amortized Cost	4,111	4,124
Due in one year or less, Carrying Value	192	183
Due after one year through five years, Carrying Value	4,184	4,199
Corporate Bond Securities
Schedule of Available-for-sale Securities
Debt securities, Cost	4,304	4,306
Debt securities, Gross Unrealized Gains	101	82
Debt securities, Gross Unrealized Losses	(29)	(6)
Debt securities, Carrying Value	4,376	4,382
Equity Securities
Schedule of Available-for-sale Securities
Marketable equity securities, Cost	9,093	10,400
Marketable equity securities, Gross Unrealized Gains	9,410	10,327
Marketable equity securities, Gross Unrealized Losses	(26)	(38)
Marketable equity securities, carrying value	$ 18,477	$ 20,689

Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt securities classified as available-for-sale.

Name:	us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt securities classified as available-for-sale.