Fair Value Measurements, Investments Measured at Fair Value on a Recurring Basis Using Significant Unobservable Inputs (Details) - Investments Valued Using Level 3 Inputs [Member] $ in Thousands	6 Months Ended
	Jun. 30, 2015 USD ($)
Investments measured at fair value on a recurring basis using significant unobservable inputs (Level 3) [Roll Forward]
Beginning balance of Level 3 investments	$ 81,881
Total gain included in accumulated other comprehensive income (loss)	22,377
Transfers out of Level 3 investments	(104,258)
Ending balance of Level 3 investments	$ 0