Marketable Securities (Details 2) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2013 Minimum Y	Sep. 30, 2013 Maximum Y	Sep. 30, 2013 Other non-current assets	Dec. 31, 2012 Other non-current assets	Sep. 30, 2013 Other non-current assets Corporate debt securities		Dec. 31, 2012 Other non-current assets Corporate debt securities		Sep. 30, 2013 Other non-current assets Mutual funds held in rabbi trusts		Dec. 31, 2012 Other non-current assets Mutual funds held in rabbi trusts
Long-term marketable securities
Long-term marketable securities maturity period	1	2
Cost			$ 9,527	$ 8,298	$ 2,250		$ 754		$ 7,277		$ 7,544
Unrealized Gain			3,111	2,085	0	[1]	1	[1]	3,111	[2]	2,084	[2]
Unrealized Loss			(1,558)	(1,495)	0	[1]	0	[1]	(1,558)	[2]	(1,495)	[2]
Fair value			$ 11,080	$ 8,888	$ 2,250		$ 755		$ 8,830		$ 8,133

[1] Unrealized gains and losses are recorded as a component of stockholders’ equity.

[2] Unrealized gains and losses are recorded in current period earnings.