Equity and Noncontrolling Interest (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Beginning Balance	$ 273,425	$ 261,705	$ 255,726	$ 187,099
Net income	11,184	13,805	35,047	35,590
Currency translation adjustments	1,600	(13,936)	(1,976)	(6,459)
Defined retirement benefit plans	436	(637)	1,405	12
Current period change in fair value of derivatives	73	112	272	286
Unrealized gain (loss) on available-for-sale securities	4	(23)	7	(17)
Dividends common stock	(3,214)	(3,091)	(9,516)	(8,881)
Dividends paid to noncontrolling interest	0		(30)
Stock offering, net of related expenses		0		48,143
Share issuance and equity-based compensation plans	973	1,304	2,126	3,304
Excess Tax Benefit From Stock Option Exercises	744	(9)	2,164	153
Ending Balance	285,225	259,230	285,225	259,230
Common Stock Member
Beginning Balance	13,011	12,823	12,912	11,492
Net income	0	0	0	0
Currency translation adjustments	0	0	0	0
Defined retirement benefit plans	0	0	0	0
Current period change in fair value of derivatives	0	0	0	0
Unrealized gain (loss) on available-for-sale securities	0	0	0	0
Dividends common stock	0	0	0	0
Dividends paid to noncontrolling interest	0		0
Stock offering, net of related expenses		0		1,265
Share issuance and equity-based compensation plans	71	52	170	118
Excess Tax Benefit From Stock Option Exercises	0	0	0	0
Ending Balance	13,082	12,875	13,082	12,875
Additional Paid-in Capital [Member]
Beginning Balance	92,199	87,249	89,725	38,275
Net income	0	0	0	0
Currency translation adjustments	0	0	0	0
Defined retirement benefit plans	0	0	0	0
Current period change in fair value of derivatives	0	0	0	0
Unrealized gain (loss) on available-for-sale securities	0	0	0	0
Dividends common stock	0	0	0	0
Dividends paid to noncontrolling interest	0		0
Stock offering, net of related expenses		0		46,878
Share issuance and equity-based compensation plans	902	1,252	1,956	3,186
Excess Tax Benefit From Stock Option Exercises	744	(9)	2,164	153
Ending Balance	93,845	88,492	93,845	88,492
Retained Earnings [Member]
Beginning Balance	192,116	158,998	175,932	144,347
Net income	10,486	13,358	32,972	33,799
Currency translation adjustments	0	0	0	0
Defined retirement benefit plans	0	0	0	0
Current period change in fair value of derivatives	0	0	0	0
Unrealized gain (loss) on available-for-sale securities	0	0	0	0
Dividends common stock	(3,214)	(3,091)	(9,516)	(8,881)
Dividends paid to noncontrolling interest	0		0
Stock offering, net of related expenses		0		0
Share issuance and equity-based compensation plans	0	0	0	0
Excess Tax Benefit From Stock Option Exercises	0	0	0	0
Ending Balance	199,388	169,265	199,388	169,265
Accumulated Other Comprehensive Income (Loss) [Member]
Beginning Balance	(32,091)	(5,507)	(29,820)	(13,736)
Net income	0	0	0	0
Currency translation adjustments	1,372	(13,042)	(2,070)	(5,642)
Defined retirement benefit plans	436	(637)	1,405	12
Current period change in fair value of derivatives	73	112	272	286
Unrealized gain (loss) on available-for-sale securities	4	(23)	7	(17)
Dividends common stock	0	0	0	0
Dividends paid to noncontrolling interest	0		0
Stock offering, net of related expenses		0		0
Share issuance and equity-based compensation plans	0	0	0	0
Excess Tax Benefit From Stock Option Exercises	0	0	0	0
Ending Balance	(30,206)	(19,097)	(30,206)	(19,097)
Noncontrolling Interest [Member]
Beginning Balance	8,190	8,142	6,977	6,721
Net income	698	447	2,075	1,791
Currency translation adjustments	228	(894)	94	(817)
Defined retirement benefit plans	0	0	0	0
Current period change in fair value of derivatives	0	0	0	0
Unrealized gain (loss) on available-for-sale securities	0	0	0	0
Dividends common stock	0	0	0	0
Dividends paid to noncontrolling interest	0		(30)
Stock offering, net of related expenses		0		0
Share issuance and equity-based compensation plans	0	0	0	0
Excess Tax Benefit From Stock Option Exercises	0	0	0	0
Ending Balance	$ 9,116	$ 7,695	$ 9,116	$ 7,695