Fair Value Measurements and Disclosures (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended			9 Months Ended
	Sep. 30, 2014		Sep. 30, 2013	Sep. 30, 2014		Sep. 30, 2013	Dec. 31, 2013
Fair value adjustment of marketable securities and deferred compensation plan liability
Net gain on marketable securities	$ (39)		$ 669	$ 507		$ 995
Trading Securities	12,076			12,076			10,008
Fair Value (Level 1) [Member]
Assets and Liabilities Reported at Fair Value
Marketable securities	$ 12,076	[1],[2]		$ 12,076	[1],[2]		$ 10,008	[1],[2]

[1] The marketable securities are held in a limited rabbi trust.

[2] Based on quoted prices in active markets for identical securities.