Quarterly Results of Operations (Unaudited) (Restated Condensed Consolidated Statements of Comprehensive Income (Loss)) (Details) - USD ($) $ in Thousands	3 Months Ended								6 Months Ended		9 Months Ended		12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2019	Jun. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Net income (loss)	$ (7,304)	$ (2,200)	$ (618)	$ (3,385)	$ 13,861	$ 7,141	$ (1,121)	$ (2,183)	$ (4,003)	$ (3,304)	$ (6,203)	$ 3,837	$ (13,507)	$ 17,698	$ 15,884
Foreign currency translation adjustment	201	(18)	113	214	(1,135)	902	(412)	573	327	161	309	1,063	510	(73)	648
Loss on long-term intra-entity foreign currency transactions	294	(509)	121	15	60	(53)	(1,013)	0	136	(1,013)	(373)	(1,066)	(79)	(1,006)	0
Cash flow hedging activity	(143)	(127)	(877)	(422)	(352)	(301)	464	289	(1,299)	753	(1,426)	452	(1,569)	100	(749)
Reclassification of hedging activities into earnings	81	122	144	2	48	(102)	41	166	146	207	268	105	349	153	641
Pension plan adjustment	1,410	0	0	0	(1,920)	0	0	0	0	0	0	0	1,410	(1,920)	1,510
Reclassification of pension adjustments into earnings	35	127	102	84	141	115	142	158	186	300	313	415	348	556	306
Total other comprehensive income (loss), net of tax	1,878	(405)	(397)	(107)	(3,158)	561	(778)	1,186	(504)	408	(909)	969	969	(2,190)	2,356
Comprehensive income (loss)	$ (5,426)	$ (2,605)	$ (1,015)	$ (3,492)	$ 10,703	$ 7,702	$ (1,899)	$ (997)	$ (4,507)	$ (2,896)	$ (7,112)	$ 4,805	$ (12,538)	$ 15,508	$ 18,240