Income Taxes - Reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Reconciliation of income tax expense computed at the federal statutory rate to the provision for income taxes
Federal income tax expense at statutory rate	$ 13,150	$ 11,709	$ 18,520
State taxes, net of federal benefit	2,239	2,349	1,539
Change in uncertain tax positions, net	(601)	(1,292)	1,043
Research and development credit	(404)	(226)	(160)
State rate change	(426)	287	240
Manufacturing tax benefits			(933)
Federal deferred rate change		(836)	(22,452)
Other	(507)	(137)	(206)
Provision for income tax expense (benefit)	$ 13,451	$ 11,854	$ (2,409)