Investments in Equity Securities Available for Sale (Investments in Equity Securities Available for Sale) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Cost	$ 306,978	$ 308,175
Gross Unrealized, Gains	95,335	70,205
Gross Unrealized, Losses	(2,927)	(2,358)
Fair Value	399,386	376,022
Carrying Value	399,386	376,022
Common Stock [Member]
Cost	224,378	222,671
Gross Unrealized, Gains	71,995	60,102
Gross Unrealized, Losses	(1,342)	(707)
Fair Value	295,031	282,066
Carrying Value	295,031	282,066
Preferred Stock [Member]
Cost	82,600	85,504
Gross Unrealized, Gains	23,340	10,103
Gross Unrealized, Losses	(1,585)	(1,651)
Fair Value	104,355	93,956
Carrying Value	$ 104,355	$ 93,956

Amount of equity securities categorized neither as held-to-maturity nor as trading.

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Reference 9: http://www.xbrl.org/2003/role/presentationRef

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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

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