Consolidated Statements of Equity (Unaudited) - USD ($) $ in Thousands	Common Stock [Member] Restricted Stock Units (RSUs) [Member]	Common Stock [Member] Performance Shares [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	AOCI Attributable to Parent [Member]	Noncontrolling Interest [Member]	Restricted Stock Units (RSUs) [Member]	Performance Shares [Member]	Total
Balance (in shares) at Dec. 31, 2017			32,462,542
Issuance of common stock upon stock option exercises (in shares)			0
Issuance of shares pursuant to restricted stock units (in shares)	301,041	296,909
Issuance of shares pursuant to deferred stock units (in shares)			26,396
Shares repurchased and retired (in shares)			(772,898)
Balance (in shares) at Sep. 30, 2018			32,313,990
Balance at Dec. 31, 2017			$ 325	$ 140,749	$ 376,694	$ (23,522)	$ 10,810			$ 505,056
Issuance of common stock upon stock option exercises			0	0						0
Issuance of shares pursuant to restricted stock units	$ 3	$ 3						$ 3	$ 3
Issuance of shares pursuant to deferred stock units			0							0
Shares repurchased and retired			(8)	(18,620)						(18,628)
Balance at Sep. 30, 2018			$ 323	128,330	382,367	(32,668)	7,732			486,084
Equity-based compensation expense				6,201						6,201
Cumulative effect adjustment (see Revenues: Note 3)					268					268
Net income (loss)					5,405		458			5,863
Currency translation adjustment and derivative transactions, net						(9,146)	(175)			(9,321)
Distributions to non-controlling interests							0			0
Sale of non-controlling interests							(3,361)			(3,361)
Balance (in shares) at Jun. 30, 2018			32,303,638
Issuance of common stock upon stock option exercises (in shares)			0
Issuance of shares pursuant to restricted stock units (in shares)	5,621	0
Issuance of shares pursuant to deferred stock units (in shares)			5,457
Shares repurchased and retired (in shares)			(726)
Balance (in shares) at Sep. 30, 2018			32,313,990
Balance at Jun. 30, 2018			$ 323	127,242	382,814	(26,374)	10,433			494,438
Issuance of common stock upon stock option exercises			0	0						0
Issuance of shares pursuant to restricted stock units	$ 0	$ 0						0	0
Issuance of shares pursuant to deferred stock units			0							0
Shares repurchased and retired			0	(19)						(19)
Balance at Sep. 30, 2018			$ 323	128,330	382,367	(32,668)	7,732			486,084
Equity-based compensation expense				1,107						1,107
Cumulative effect adjustment (see Revenues: Note 3)					0					0
Net income (loss)					(447)		588			141
Currency translation adjustment and derivative transactions, net						(6,294)	72			(6,222)
Distributions to non-controlling interests							0			0
Sale of non-controlling interests							(3,361)			$ (3,361)
Balance (in shares) at Dec. 31, 2018			31,922,409							31,922,409
Issuance of common stock upon stock option exercises (in shares)			52,783							52,783
Issuance of shares pursuant to restricted stock units (in shares)	222,745	111,158
Issuance of shares pursuant to deferred stock units (in shares)			84,184
Shares repurchased and retired (in shares)			(1,585,731)
Balance (in shares) at Sep. 30, 2019			30,807,548							30,807,548
Balance at Dec. 31, 2018			$ 319	122,818	379,890	(40,290)	7,450			$ 470,187
Issuance of common stock upon stock option exercises			1	955						956
Issuance of shares pursuant to restricted stock units	$ 2	$ 1						2	1
Issuance of shares pursuant to deferred stock units			1							1
Shares repurchased and retired			(16)	(28,127)						(28,143)
Balance at Sep. 30, 2019			$ 308	101,627	373,559	(43,626)	6,576			438,444
Equity-based compensation expense				5,981						5,981
Cumulative effect adjustment (see Revenues: Note 3)					0					0
Net income (loss)					(6,331)		542			(5,789)
Currency translation adjustment and derivative transactions, net						(3,336)	(7)			(3,343)
Distributions to non-controlling interests							(1,409)			(1,409)
Sale of non-controlling interests							0			$ 0
Balance (in shares) at Jun. 30, 2019			30,941,394
Issuance of common stock upon stock option exercises (in shares)			0
Issuance of shares pursuant to restricted stock units (in shares)	17,471	0
Issuance of shares pursuant to deferred stock units (in shares)			6,698
Shares repurchased and retired (in shares)			(158,015)
Balance (in shares) at Sep. 30, 2019			30,807,548							30,807,548
Balance at Jun. 30, 2019			$ 309	102,841	367,523	(42,940)	6,290			$ 434,023
Issuance of common stock upon stock option exercises			0	0						0
Issuance of shares pursuant to restricted stock units	$ 0	$ 0						$ 0	$ 0
Issuance of shares pursuant to deferred stock units			0							0
Shares repurchased and retired			(1)	(2,971)						(2,972)
Balance at Sep. 30, 2019			$ 308	101,627	373,559	(43,626)	6,576			438,444
Equity-based compensation expense				$ 1,757						1,757
Cumulative effect adjustment (see Revenues: Note 3)					0					0
Net income (loss)					$ 6,036		313			6,349
Currency translation adjustment and derivative transactions, net						$ (686)	(27)			(713)
Distributions to non-controlling interests							0			0
Sale of non-controlling interests							$ 0			$ 0