Investments in Equity Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Cost	$ 163,656	$ 165,192
Gross Unrealized, Gains	6,788	8,216
Gross Unrealized, Losses	(11,469)	(22,542)
Carrying and fair value of equity securities	158,975	150,866
Common stocks
Schedule of Available-for-sale Securities [Line Items]
Cost	37,897	56,462
Gross Unrealized, Gains	215	0
Gross Unrealized, Losses	(2,441)	(19,189)
Carrying and fair value of equity securities	35,671	37,273
Preferred stocks
Schedule of Available-for-sale Securities [Line Items]
Cost	125,759	108,730
Gross Unrealized, Gains	6,573	8,216
Gross Unrealized, Losses	(9,028)	(3,353)
Carrying and fair value of equity securities	$ 123,304	$ 113,593