Marketable Securities - Additional Information (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Schedule of Available-for-sale Securities [Line Items]
Fair market value of investment securities exceeds cost basis	$ 247,000		$ 247,000
Other-than-temporary impairments recorded for securities	0		0
Changes in unrealized gains on available for sale securities, taxes	(1,000)	(409,000)	11,000	(452,000)
Estimated taxes of change in value of available-for-sale securities			4,000
Gross unrealized holding gains			299,000
Gross unrealized holding losses			$ 52,000