Marketable Securities (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	$ 25,299	$ 26,096
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	198	117
Gross unrealized holding losses	(50)	(57)
Estimated fair value	25,447us-gaap_AvailableForSaleSecurities	26,156us-gaap_AvailableForSaleSecurities
Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	19,220
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	162
Gross unrealized holding losses	(48)
Estimated fair value	19,334
Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	6,079
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	36
Gross unrealized holding losses	(2)
Estimated fair value	$ 6,113

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

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