Fair Value Of Financial Instruments (Quantitative Information related To The Significant Unobservable Inputs Utilized In Company's Level 3 Recurring Fair Value Measurements) (Details)	12 Months Ended
	Dec. 31, 2012
State And Municipal Securities [Member]
Discount rate range, low end	1.90%
Discount rate range, high end	10.00%
Workout period range, low end	2 years
Workout period range, high end	4 years
Auction Rate Equity Securities [Member]
Discount rate range, low end	1.60%
Discount rate range, high end	12.10%
Workout period range, low end	1 year
Workout period range, high end	3 years
Auction Rate Municipal Securities [Member]
Discount rate range, low end	0.50%
Discount rate range, high end	10.30%
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	5.60%
Weighted average workout period	3 years 4 months 24 days
Discounted Cash Flow [Member] | Auction Rate Equity Securities [Member]
Discount rate, weighted average	7.20%
Weighted average workout period	2 years 8 months 12 days
Discounted Cash Flow [Member] | Auction Rate Municipal Securities [Member]
Discount rate, weighted average	5.80%
Weighted average workout period	2 years 7 months 6 days
Maximum [Member] | Investments In Partnerships [Member]
Revenue multiple	4.0
EBITDA multiple	14.6
Maximum [Member] | Private Equity Investments [Member]
Revenue multiple	3.4
EBITDA multiple	17.8
Minimum [Member] | Investments In Partnerships [Member]
Revenue multiple	1.4
EBITDA multiple	7.0
Minimum [Member] | Private Equity Investments [Member]
Revenue multiple	0.5
EBITDA multiple	4.4
Weighted Average [Member] | Market Approach [Member] | Investments In Partnerships [Member]
Revenue multiple	2.8
EBITDA multiple	9.3
Weighted Average [Member] | Market Approach [Member] | Private Equity Investments [Member]
Revenue multiple	2.1
EBITDA multiple	10.1