Trust Account and Fair Value Measurement (Details) - USD ($) |
9 Months Ended | 12 Months Ended |
|---|---|---|
Sep. 30, 2018 |
Dec. 31, 2017 |
|
| Assets: | ||
| Carrying value | $ 302,854,000 | $ 300,403,000 |
| Gross Unrealized Holding Gain (Loss) | (70,000) | |
| Cash and money market [Member] | ||
| Assets: | ||
| Carrying value | 1,000 | |
| Gross Unrealized Holding Gain (Loss) | ||
| U.S. government treasury bills [Member] | ||
| Assets: | ||
| Carrying value | 302,853,000 | 300,403,000 |
| Gross Unrealized Holding Gain (Loss) | (70,000) | 18,000 |
| Quoted Price Prices in Active Markets (Level 1) [Member] | ||
| Assets: | ||
| Gross Unrealized Holding Gain (Loss) | 302,784,000 | |
| Quoted Price Prices in Active Markets (Level 1) [Member] | Cash and money market [Member] | ||
| Assets: | ||
| Carrying value | 1,000 | |
| Quoted Price Prices in Active Markets (Level 1) [Member] | U.S. government treasury bills [Member] | ||
| Assets: | ||
| Carrying value | $ 302,783,000 | $ 300,421,000 |