Fair Value Measurements (Summary Of Quantitative Information About Level 3 Fair Value Measurements) (Details)	3 Months Ended
	Mar. 31, 2013
Auction Rate Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Valuation Technique, Discounted cash flow	Discounted cash flow
Unobservable Input, Estimated market recovery period	5 years
Auction Rate Securities [Member] | Minimum [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Unobservable Input, Estimated market rate	2.20%
Auction Rate Securities [Member] | Maximum [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Unobservable Input, Estimated market rate	3.50%
Private Equity Investments [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Valuation Technique, Market comparable companies	Market comparable companies
Private Equity Investments [Member] | Minimum [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Unobservable Input, EBITDA multiple	4.0
Private Equity Investments [Member] | Maximum [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Unobservable Input, EBITDA multiple	5.4