Investments in Equity Securities (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Cost	$ 170,860	$ 160,295
Gross Unrealized, Gains	17,102	20,314
Gross Unrealized, Losses	(13,253)	(9,618)
Carrying and fair value of equity securities	174,709	170,991
Common stocks
Schedule of Available-for-sale Securities [Line Items]
Cost	70,483	69,870
Gross Unrealized, Gains	0	11,929
Gross Unrealized, Losses	(9,383)	(5,453)
Carrying and fair value of equity securities	61,100	76,346
Preferred stocks
Schedule of Available-for-sale Securities [Line Items]
Cost	100,377	90,425
Gross Unrealized, Gains	17,102	8,385
Gross Unrealized, Losses	(3,870)	(4,165)
Carrying and fair value of equity securities	$ 113,609	$ 94,645