Securities In An Unrealized Loss Position Securities In An Unrealized Loss Position (Narrative) (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Schedule of Available-for-sale Securities [Line Items]
Aggregate fair value of securities in a continuous unrealized loss position	$ 3,001,158	$ 1,536,923
Gross Unrealized Losses	103,312	35,018
Preferred stocks
Schedule of Available-for-sale Securities [Line Items]
Aggregate fair value of securities in a continuous unrealized loss position	46,845	39,812
Gross Unrealized Losses	7,636	1,651
Preferred stocks | Noninvestment Grade Investments [Member]
Schedule of Available-for-sale Securities [Line Items]
Number of securities	4
Aggregate fair value of securities in a continuous unrealized loss position	47,000
Gross Unrealized Losses	8,000
Common stocks
Schedule of Available-for-sale Securities [Line Items]
Aggregate fair value of securities in a continuous unrealized loss position	36,899	46,725
Gross Unrealized Losses	5,576	707
Common stocks | Noninvestment Grade Investments [Member]
Schedule of Available-for-sale Securities [Line Items]
Number of securities	2
Aggregate fair value of securities in a continuous unrealized loss position	37,000
Gross Unrealized Losses	$ 6,000