Securities in an Unrealized Loss Position (Narrative) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Schedule of Available-for-sale Securities [Line Items]
Securities in continuous unrealized loss position fair value	$ 3,441,075	$ 1,536,923
Securities in continuous unrealized loss position, aggregate losses accumulated In AOCI	117,453	35,018
Preferred stocks
Schedule of Available-for-sale Securities [Line Items]
Securities in unrealized loss positions	3
Securities in continuous unrealized loss position fair value	33,159	39,812
Securities in continuous unrealized loss position, aggregate losses accumulated In AOCI	6,319	1,651
Common stocks
Schedule of Available-for-sale Securities [Line Items]
Securities in unrealized loss positions	0
Securities in continuous unrealized loss position fair value	0	46,725
Securities in continuous unrealized loss position, aggregate losses accumulated In AOCI	$ 0	$ 707