Investments in Equity Securities Available for Sale (Investments in Equity Securities Available for Sale) (Details) (USD $)	Dec. 31, 2011	Dec. 31, 2010
Cost	$ 342,393,000	$ 404,235,000
Gross Unrealized, Gains	118,799,000	168,482,000
Gross Unrealized, Losses	(17,753,000)	(11,664,000)
Fair Value	443,439,000	561,053,000
Carrying Value	443,439,000	561,053,000
Common Stocks [Member]
Cost	209,210,000	188,949,000
Gross Unrealized, Gains	113,660,000	128,096,000
Gross Unrealized, Losses	(2,888,000)	(989,000)
Fair Value	319,982,000	316,056,000
Carrying Value	319,982,000	316,056,000
Preferred Stocks [Member]
Cost	133,183,000	215,286,000
Gross Unrealized, Gains	5,139,000	40,386,000
Gross Unrealized, Losses	(14,865,000)	(10,675,000)
Fair Value	123,457,000	244,997,000
Carrying Value	$ 123,457,000	$ 244,997,000