Investments (Tables)
|
6 Months Ended |
Jun. 30, 2018 |
|---|
| Available For Sale Securities |
|
| Gain (Loss) on Investments [Line Items] |
|
| Summary of the cost and fair value of investments |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Gross Unrealized
|
|
Fair
|
|
|
|
Cost
|
|
Gains
|
|
(Losses)
|
|
Value
|
|
As of June 30, 2018
|
|
$
|
595
|
|
$
|
106
|
|
$
|
—
|
|
$
|
701
|
|
As of December 31, 2017
|
|
|
595
|
|
|
82
|
|
|
—
|
|
|
677
|
|
| Trading Securities. |
|
| Gain (Loss) on Investments [Line Items] |
|
| Cost and fair value of investments |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Gross Unrealized
|
|
Fair
|
|
|
|
Cost
|
|
Gains
|
|
(Losses)
|
|
Value
|
|
As of June 30, 2018
|
|
$
|
11,989
|
|
$
|
1,002
|
|
$
|
(226)
|
|
$
|
12,765
|
|
As of December 31, 2017
|
|
|
9,978
|
|
|
950
|
|
|
(269)
|
|
|
10,659
|
|
| Summary of proceeds and realized gains and losses |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Sale
|
|
Realized
|
|
|
|
Proceeds
|
|
Gains
|
|
(Losses)
|
|
For the Three Months Ended June 30, 2018
|
|
$
|
180
|
|
$
|
5
|
|
$
|
(4)
|
|
For the Three Months Ended June 30, 2017
|
|
|
264
|
|
|
18
|
|
|
(9)
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Sale
|
|
Realized
|
|
|
|
Proceeds
|
|
Gains
|
|
(Losses)
|
|
For the Six Months Ended June 30, 2018
|
|
$
|
628
|
|
$
|
33
|
|
$
|
(6)
|
|
For the Six Months Ended June 30, 2017
|
|
|
1,201
|
|
|
27
|
|
|
(15)
|
|
|
|
|
|
|
|
|
|
|
|
|