Fair Value Of Financial Instruments (Quantitative Information related To The Significant Unobservable Inputs Utilized In Company's Level 3 Recurring Fair Value Measurements) (Details)	3 Months Ended
	Mar. 31, 2013
State And Municipal Securities [Member]
Discount rate range, low end	1.80%
Discount rate range, high end	9.70%
Workout period range, low end	2 years
Workout period range, high end	4 years
Auction Rate Equity Securities [Member]
Discount rate range, low end	2.00%
Discount rate range, high end	11.70%
Workout period range, low end	1 year
Workout period range, high end	3 years
Auction Rate Municipal Securities [Member]
Discount rate range, low end	0.00%
Discount rate range, high end	10.00%
Workout period range, low end	1 year
Workout period range, high end	4 years
Discounted Cash Flow [Member] | State And Municipal Securities [Member]
Discount rate, weighted average	5.50%
Weighted average workout period	3 years 4 months 24 days
Discounted Cash Flow [Member] | Auction Rate Equity Securities [Member]
Discount rate, weighted average	6.90%
Weighted average workout period	2 years 9 months 18 days
Discounted Cash Flow [Member] | Auction Rate Municipal Securities [Member]
Discount rate, weighted average	5.60%
Weighted average workout period	2 years 7 months 6 days
Minimum [Member] | Investments In Partnerships [Member]
Revenue multiple	1.3
EBITDA multiple	7.0
Minimum [Member] | Private Equity Investments [Member]
Revenue multiple	0.5
EBITDA multiple	4.3
Weighted Average [Member] | Market Approach [Member] | Investments In Partnerships [Member]
Revenue multiple	2.7
EBITDA multiple	9.1
Weighted Average [Member] | Market Approach [Member] | Private Equity Investments [Member]
Revenue multiple	2.2
EBITDA multiple	10.0