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	9 Months Ended
	Sep. 30, 2015 USD ($)
Unobservable Inputs (Level 3) Reconciliation [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