Investments (Narrative) (Details) (USD $)			3 Months Ended
	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2014 Minimum [Member]	Mar. 31, 2014 Maximum [Member]
Schedule of Investments [Line Items]
Certificates of deposits	$ 9,300,000	$ 10,700,000
Certificates of deposit interest rate, lower range	0.20%
Certificates of deposit interest rate, upper range	0.90%
Certificates of deposit maturity dates			1 month	13 months
Investments held to maturity	$ 23,835,000	$ 27,021,000
Investments maturity dates			1 month	13 months