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 |