Intangible assets - Carrying Amount (Details) - USD ($) $ in Thousands |
Dec. 31, 2017 |
Dec. 31, 2016 |
Dec. 31, 2015 |
|---|---|---|---|
| Intangible assets | |||
| Historical Cost | $ 28,905 | $ 31,815 | |
| Accumulated Amortization | (18,642) | (18,032) | |
| Net | 10,263 | 13,783 | $ 16,055 |
| Venue contracts | |||
| Intangible assets | |||
| Historical Cost | 22,061 | 23,601 | |
| Accumulated Amortization | (13,835) | (13,276) | |
| Net | 8,226 | 10,325 | |
| Non-compete agreements | |||
| Intangible assets | |||
| Historical Cost | 3,590 | 3,590 | |
| Accumulated Amortization | (2,992) | (2,274) | |
| Net | 598 | 1,316 | |
| Technology | |||
| Intangible assets | |||
| Historical Cost | 2,410 | 3,520 | |
| Accumulated Amortization | (1,265) | (1,742) | |
| Net | 1,145 | 1,778 | |
| Advertiser relationships | |||
| Intangible assets | |||
| Historical Cost | 70 | ||
| Accumulated Amortization | (62) | ||
| Net | 8 | ||
| Patents, trademarks and other | |||
| Intangible assets | |||
| Historical Cost | 844 | 1,034 | |
| Accumulated Amortization | (550) | (678) | |
| Net | $ 294 | $ 356 |