Investments in Equity Securities Available for Sale (Investments in Equity Securities Available for Sale) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Cost	$ 160,295	$ 203,627
Gross Unrealized, Gains	20,314	86,030
Gross Unrealized, Losses	(9,618)	(6,319)
Carrying value and fair value of equity securities	170,991	283,338
Common stocks
Schedule of Available-for-sale Securities [Line Items]
Cost	69,870	118,536
Gross Unrealized, Gains	11,929	42,239
Gross Unrealized, Losses	(5,453)	0
Carrying value and fair value of equity securities	76,346	160,775
Preferred stocks
Schedule of Available-for-sale Securities [Line Items]
Cost	90,425	85,091
Gross Unrealized, Gains	8,385	43,791
Gross Unrealized, Losses	(4,165)	(6,319)
Carrying value and fair value of equity securities	$ 94,645	$ 122,563