Investments in Equity Securities (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Cost	$ 145,676	$ 165,192
Gross Unrealized, Gains	8,006	8,216
Gross Unrealized, Losses	(11,983)	(22,542)
Carrying and fair value of equity securities	141,699	150,866
Common stocks
Schedule of Available-for-sale Securities [Line Items]
Cost	38,686	56,462
Gross Unrealized, Gains	424	0
Gross Unrealized, Losses	(1,539)	(19,189)
Carrying and fair value of equity securities	37,571	37,273
Preferred stocks
Schedule of Available-for-sale Securities [Line Items]
Cost	106,990	108,730
Gross Unrealized, Gains	7,582	8,216
Gross Unrealized, Losses	(10,444)	(3,353)
Carrying and fair value of equity securities	$ 104,128	$ 113,593