Fair Value Measurements and Disclosures (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015		Sep. 30, 2013	Dec. 31, 2014
Fair value adjustment of marketable securities and deferred compensation plan liability
Net gain on marketable securities	$ 388		$ 154
Trading Securities	13,337			11,971
Fair Value (Level 1) [Member]
Assets and Liabilities Reported at Fair Value
Marketable securities	$ 13,337	[1],[2]		$ 11,971	[1],[2]

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

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