Fair Value Measurements (Details 2) (Investments Valued Using Level 3 Inputs [Member], USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Investments Valued Using Level 3 Inputs [Member]
Investments measured at fair value on a recurring basis using significant unobservable inputs (Level 3) [Roll Forward]
Balance at the beginning of the period	$ 0	$ 34,350
Total gains and losses included in gain on investments	0	(1,163)
Total gains and losses included in accumulated other comprehensive income (loss)	1,918	11,716
Cost basis of shares sold	0	(40)
Balance at the end of the period	$ 1,918	$ 44,863