Securities In An Unrealized Loss Position Securities In An Unrealized Loss Position (Narrative) (Details) - USD ($)	Mar. 31, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Aggregate fair value of securities in a continuous unrealized loss position	$ 2,757,788,000	$ 4,170,376,000
Gross Unrealized Losses	89,094,000	113,948,000
Available For Sale Equity Securities Gross Unrealized Gains	8,006,000	8,216,000
Loans and Leases Receivable, Other, Allowance	$ 3,000,000	2,000,000
Noninvestment Grade Investments [Member]
Schedule of Available-for-sale Securities [Line Items]
Number of Securities	5
Preferred stocks
Schedule of Available-for-sale Securities [Line Items]
Aggregate fair value of securities in a continuous unrealized loss position	$ 62,898,000	22,320,000
Gross Unrealized Losses	10,444,000	3,353,000
Available For Sale Equity Securities Gross Unrealized Gains	7,582,000	8,216,000
Common stocks
Schedule of Available-for-sale Securities [Line Items]
Aggregate fair value of securities in a continuous unrealized loss position	7,474,000	26,470,000
Gross Unrealized Losses	1,539,000	19,189,000
Available For Sale Equity Securities Gross Unrealized Gains	424,000	$ 0
Common stocks
Schedule of Available-for-sale Securities [Line Items]
Available For Sale Equity Securities Gross Unrealized Gains	$ 1,500,000