Acquisitions - Unaudited Pro Forma Operating Results (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
(Actual)
Net sales	$ 218,025	$ 191,660
Net income	$ 3,890	$ 11,054
Earnings per share:
Basic (USD per share)	$ 0.23	$ 0.64
Diluted (USD per share)	$ 0.22	$ 0.64
Basic (shares)	17,254	17,164
Diluted (shares)	17,318	17,339
Interface
(Actual)
Net sales	$ 218,025
Net income	$ 3,890
Earnings per share:
Basic (USD per share)	$ 0.23
Diluted (USD per share)	$ 0.22
Basic (shares)	17,254
Diluted (shares)	17,318
(Pro Forma)
Net sales		$ 231,077
Net income		$ 10,946
Earnings per share:
Basic (USD per share)		$ 0.64
Diluted (USD per share)		$ 0.63
Basic (shares)		17,164
Diluted (shares)		17,339