Investments In Marketable Securities (Narrative) (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Marketable Securities [Abstract]
Gross unrealized gains related to available for sale securities	$ 37,492	$ 34,667

Amount before tax of unrealized gain (loss) in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

No definition available.

Name:	us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainLossBeforeTax
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant