Assets and Liabilities Measured at Fair Value (Details) - USD ($) |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2017 |
Dec. 31, 2016 |
Dec. 31, 2015 |
|
| Realized and Unrealized Gains (Losses) on Financial Instruments | |||
| Realized and unrealized gains (losses) | $ 3,098,000 | $ 94,122,000 | $ 2,619,000 |
| Zero-strike call option | |||
| Realized and Unrealized Gains (Losses) on Financial Instruments | |||
| Realized and unrealized gains (losses) | $ 3,098,000 | 1,132,000 | |
| Time Warner Cable | Investment and financial instruments [member] | |||
| Realized and Unrealized Gains (Losses) on Financial Instruments | |||
| Realized and unrealized gains (losses) | $ 92,990,000 | $ 2,619,000 | |
| X | ||||||||||
- Definition This item represents the amount of the total realized and unrealized gains or losses for the period which are included in the statement of income (or changes in net assets); the fair value of which assets and liabilities was or is measured on a recurring basis using significant unobservable inputs (Level 3). Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. No definition available.
|
| X | ||||||||||
- Details
|
| X | ||||||||||
- Details
|
| X | ||||||||||
- Details
|