Investments in Equity Securities Available for Sale (Investments in Equity Securities Available for Sale) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Cost	$ 376,579	$ 342,393
Gross Unrealized, Gains	120,099	118,799
Gross Unrealized, Losses	(7,458)	(17,753)
Fair Value	489,220	443,439
Carrying Value	489,220	443,439
Common Stock [Member]
Cost	253,900	209,210
Gross Unrealized, Gains	112,072	113,660
Gross Unrealized, Losses	(735)	(2,888)
Fair Value	365,237	319,982
Carrying Value	365,237	319,982
Preferred Stock [Member]
Cost	122,679	133,183
Gross Unrealized, Gains	8,027	5,139
Gross Unrealized, Losses	(6,723)	(14,865)
Fair Value	123,983	123,457
Carrying Value	$ 123,983	$ 123,457

For an unclassified balance sheet, this item represents equity securities categorized neither as held-to-maturity nor trading.

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Reference 10: http://www.xbrl.org/2003/role/presentationRef

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