Goodwill - Schedule of Changes in Goodwill (Detail) - USD ($) $ in Thousands |
3 Months Ended | 12 Months Ended |
|---|---|---|
Mar. 31, 2019 |
Dec. 31, 2018 |
|
| Goodwill [Line Items] | ||
| Balance, beginning of period before cumulative loss on impairment | $ 28,818 | $ 28,453 |
| Beginning Balance, Accumulated loss on impairment | (2,029) | (2,029) |
| Balance, beginning of period after cumulative loss on impairment | 26,789 | 26,424 |
| Balance, end of period before cumulative loss on impairment | 28,474 | 28,818 |
| Ending Balance, Accumulated loss on impairment | (2,029) | (2,029) |
| Ending period balance | 26,445 | 26,789 |
| Radio Stations [Member] | ||
| Goodwill [Line Items] | ||
| Acquisitions | 7 | |
| Goodwill, Written off Related to Sale of Business Unit | (3) | (628) |
| Digital Media [Member] | ||
| Goodwill [Line Items] | ||
| Acquisitions | $ 986 | |
| Goodwill, Written off Related to Sale of Business Unit | $ (341) |
| X | ||||||||||
- Definition Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
|
| X | ||||||||||
- Definition Amount of increase in asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized resulting from a business combination. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
|
| X | ||||||||||
- Definition Amount before accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
|
| X | ||||||||||
- Definition Amount of accumulated impairment loss for an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
|
| 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 | ||||||||||
- Definition Amount of divestiture of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
|
| X | ||||||||||
- Details
|
| X | ||||||||||
- Details
|