Investing Receivables (Tables)  | 
12 Months Ended | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Dec. 31, 2017  | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Receivables [Abstract] | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Schedule of investing receivables | 
 Investing receivables, including accrued interest thereon, consisted of the following (in thousands): 
  | 
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| X | ||||||||||
- Definition Tabular disclosure of the carrying amounts of mortgage and other investing receivables, by major class. No definition available. 
  | 
| X | ||||||||||
- References No definition available. 
  |