Fair Value Of Financial Instruments (Quantitative Information related To The Significant Unobservable Inputs Utilized In Company's Level 3 Recurring Fair Value Measurements) (Details)	9 Months Ended
	Sep. 30, 2012
Discounted Cash Flow [Member] | State And Municipal Securities [Member]
Discount rate range, low end	1.80%
Discount rate range, high end	9.60%
Discount rate, weighted average	4.90%
Workout period range, low end	2 years
Workout period range, high end	4 years
Weighted average workout period	3 years 1 month 6 days
Discounted Cash Flow [Member] | Auction Rate Equity Securities [Member]
Discount rate range, low end	1.50%
Discount rate range, high end	11.70%
Discount rate, weighted average	6.80%
Workout period range, low end	1 year
Workout period range, high end	3 years
Weighted average workout period	2 years 8 months 12 days
Discounted Cash Flow [Member] | Auction Rate Municipal Securities [Member]
Discount rate range, low end	0.40%
Discount rate range, high end	10.00%
Discount rate, weighted average	5.00%
Workout period range, low end	1 year
Workout period range, high end	4 years
Weighted average workout period	2 years 7 months 6 days
Maximum [Member] | Market Approach [Member] | Investments In Partnerships [Member]
Revenue multiple	370
EBITDA multiple	1,460
Maximum [Member] | Market Approach [Member] | Private Equity Investments [Member]
Revenue multiple	320
EBITDA multiple	1,740
Minimum [Member] | Market Approach [Member] | Investments In Partnerships [Member]
Revenue multiple	150
EBITDA multiple	630
Minimum [Member] | Market Approach [Member] | Private Equity Investments [Member]
Revenue multiple	140
EBITDA multiple	780
Weighted Average [Member] | Market Approach [Member] | Investments In Partnerships [Member]
Revenue multiple	280
EBITDA multiple	1,040
Weighted Average [Member] | Market Approach [Member] | Private Equity Investments [Member]
Revenue multiple	280
EBITDA multiple	1,250