Investments in Equity Securities Available for Sale (Investments in Equity Securities Available for Sale) (Details) (USD $)	Dec. 31, 2012	Dec. 31, 2011
Cost	$ 308,175,000	$ 342,393,000
Gross Unrealized, Gains	70,205,000	118,799,000
Gross Unrealized, Losses	(2,358,000)	(17,753,000)
Fair Value	376,022,000	443,439,000
Carrying Value	376,022,000	443,439,000
Common Stocks [Member]
Cost	222,671,000	209,210,000
Gross Unrealized, Gains	60,102,000	113,660,000
Gross Unrealized, Losses	(707,000)	(2,888,000)
Fair Value	282,066,000	319,982,000
Carrying Value	282,066,000	319,982,000
Preferred Stocks [Member]
Cost	85,504,000	133,183,000
Gross Unrealized, Gains	10,103,000	5,139,000
Gross Unrealized, Losses	(1,651,000)	(14,865,000)
Fair Value	93,956,000	123,457,000
Carrying Value	$ 93,956,000	$ 123,457,000