Industry, Segment and Geographic Information - Sales and Assets (Details) $ in Thousands |
3 Months Ended | 12 Months Ended | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
|
Dec. 31, 2017
USD ($)
country
|
Sep. 30, 2017
USD ($)
|
Jun. 30, 2017
USD ($)
|
Mar. 31, 2017
USD ($)
|
Dec. 31, 2016
USD ($)
country
|
Sep. 30, 2016
USD ($)
|
Jun. 30, 2016
USD ($)
|
Mar. 31, 2016
USD ($)
|
Dec. 31, 2017
USD ($)
country
|
Dec. 31, 2016
USD ($)
country
|
Dec. 31, 2015
USD ($)
country
|
|
| Net sales to unaffiliated customers and identifiable assets by geographic areas | |||||||||||
| Number of countries other than USA that make up 10% or more of net sales | country | 0 | 0 | 0 | 0 | 0 | ||||||
| Net sales to Unaffiliated Customers | $ 126,956 | $ 106,646 | $ 102,982 | $ 112,795 | $ 119,965 | $ 99,586 | $ 105,257 | $ 93,323 | $ 449,379 | $ 418,131 | $ 382,090 |
| Identifiable Assets by Geographic Areas | 102,725 | 113,698 | 102,725 | 113,698 | 94,082 | ||||||
| USA | |||||||||||
| Net sales to unaffiliated customers and identifiable assets by geographic areas | |||||||||||
| Net sales to Unaffiliated Customers | 389,925 | 364,989 | 336,110 | ||||||||
| Identifiable Assets by Geographic Areas | 95,516 | 106,014 | 95,516 | 106,014 | 87,679 | ||||||
| Canada | |||||||||||
| Net sales to unaffiliated customers and identifiable assets by geographic areas | |||||||||||
| Net sales to Unaffiliated Customers | 30,289 | 28,491 | 23,957 | ||||||||
| Identifiable Assets by Geographic Areas | $ 7,209 | $ 7,684 | 7,209 | 7,684 | 6,403 | ||||||
| Rest of the world | |||||||||||
| Net sales to unaffiliated customers and identifiable assets by geographic areas | |||||||||||
| Net sales to Unaffiliated Customers | $ 29,165 | $ 24,651 | $ 22,023 | ||||||||