Financial Instruments (Maturity Periods for Investments) (Details)	6 Months Ended
	Jun. 30, 2016
Corporate bond securities [Member] | Minimum [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment maturity term	1 month
Corporate bond securities [Member] | Maximum {Member]
Schedule of Available-for-sale Securities [Line Items]
Investment maturity term	5 years
US Government Agencies Debt Securities [Member] | Minimum [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment maturity term	1 year
US Government Agencies Debt Securities [Member] | Maximum {Member]
Schedule of Available-for-sale Securities [Line Items]
Investment maturity term	3 years
Mortgage backed securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment maturity term	5 years
Asset-backed securities [Member] | Minimum [Member]
Schedule of Available-for-sale Securities [Line Items]
Investment maturity term	1 year
Asset-backed securities [Member] | Maximum {Member]
Schedule of Available-for-sale Securities [Line Items]
Investment maturity term	5 years