Fair Value Of Financial Instruments (Quantitative Information related To The Significant Unobservable Inputs Utilized In Company's Level 3 Recurring Fair Value Measurements) (Details) - Discounted Cash Flow [Member]	9 Months Ended
	Sep. 30, 2016
Auction Rate Equity Securities [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Workout period range, low end	1 year
Workout period range, high end	3 years
Discount rate, weighted average	5.80%
Weighted average workout period	2 years 6 months
Auction Rate Equity Securities [Member] | Minimum [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Discount rate range	1.80%
Auction Rate Equity Securities [Member] | Maximum [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Discount rate range	11.70%
Auction Rate Municipal Securities [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Workout period range, low end	1 year
Workout period range, high end	4 years
Discount rate, weighted average	4.90%
Weighted average workout period	2 years 1 month 6 days
Auction Rate Municipal Securities [Member] | Minimum [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Discount rate range	0.00%
Auction Rate Municipal Securities [Member] | Maximum [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Discount rate range	10.40%