Annual report pursuant to Section 13 and 15(d)

Available-for-Sale Securities, at Fair Value Schedule of Realized Gain (Loss) (Details)

v3.8.0.1
Available-for-Sale Securities, at Fair Value Schedule of Realized Gain (Loss) (Details) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]      
Available-for-sale Securities, Gross Realized Gains (Losses), Sale Proceeds $ 8,673,794 $ 14,404,457 $ 6,985,567
Available-for-sale Securities, Gross Realized Gains (Losses), Amortized Cost Sold 8,706,285 14,530,685 6,616,215
Gross realized gains 67,764 97,049 388,392
Gross realized losses (100,255) (223,277) (19,040)
Total realized (losses) gains on sales, net $ (32,491) $ (126,228) $ 369,352