Marketable Securities - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Investments, Debt and Equity Securities [Abstract]
Fair market value of investment securities exceeds cost basis	$ 29		$ 29
Changes in unrealized gains on available for sale securities, taxes	(119)	$ (1)	(57)	$ 11
Estimated taxes of change in value of available-for-sale securities			23
Gross unrealized holding gains	88		88
Gross unrealized holding losses	$ 117		$ 117