Summary of Significant Accounting Policies - Warranty Costs (Details) - USD ($) $ in Thousands |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2016 |
Dec. 31, 2015 |
Dec. 31, 2014 |
|
| Changes in the warranty reserve | |||
| Accrued warranty reserve, beginning of period | $ 3,333 | $ 1,528 | $ 638 |
| Reserve provided | 3,864 | 3,974 | 1,495 |
| Payments | (3,164) | (2,169) | (605) |
| Accrued warranty reserve, end of period | $ 4,033 | $ 3,333 | $ 1,528 |