Investments in Equity Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Cost	$ 183,165	$ 160,295
Gross Unrealized, Gains	20,756	20,314
Gross Unrealized, Losses	(26,044)	(9,618)
Carrying and fair value of equity securities	177,877	170,991
Common stocks
Schedule of Available-for-sale Securities [Line Items]
Cost	64,382	69,870
Gross Unrealized, Gains	0	11,929
Gross Unrealized, Losses	(22,254)	(5,453)
Carrying and fair value of equity securities	42,128	76,346
Preferred stocks
Schedule of Available-for-sale Securities [Line Items]
Cost	118,783	90,425
Gross Unrealized, Gains	20,756	8,385
Gross Unrealized, Losses	(3,790)	(4,165)
Carrying and fair value of equity securities	$ 135,749	$ 94,645