Equity and Noncontrolling Interest (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Balance at	$ 270,664	$ 200,762	$ 255,726	$ 187,099
Net income	11,170	10,555	23,863	21,785
Currency translation adjustments	(7,211)	3,656	(3,576)	7,477
Defined retirement benefit plans	499	325	969	649
Current period change in fair value of derivatives	103	78	199	174
Unrealized (loss) gain on available-for-sale securities	(5)	0	3	6
Dividends common stock	(3,188)	(3,080)	(6,302)	(5,790)
Dividends paid to noncontrolling interest	(30)		(30)
Stock offering, net of related expenses		48,143		48,143
Share issuance and equity-based compensation plans	1,255	1,182	1,153	2,000
Excess Tax Benefit From Stock Option Exercises	168	84	1,420	162
Balance at	273,425	261,705	273,425	261,705
Common Stock Member
Balance at	12,951	11,531	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 (loss) gain on available-for-sale securities	0	0	0	0
Dividends common stock	0	0	0	0
Dividends paid to noncontrolling interest			0
Stock offering, net of related expenses		1,265		1,265
Share issuance and equity-based compensation plans	60	27	99	66
Excess Tax Benefit From Stock Option Exercises	0	0	0	0
Balance at	13,011	12,823	13,011	12,823
Additional Paid-in Capital [Member]
Balance at	90,836	39,132	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 (loss) gain on available-for-sale securities	0	0	0	0
Dividends common stock	0	0	0	0
Dividends paid to noncontrolling interest			0
Stock offering, net of related expenses		46,878		46,878
Share issuance and equity-based compensation plans	1,195	1,155	1,054	1,934
Excess Tax Benefit From Stock Option Exercises	168	84	1,420	162
Balance at	92,199	87,249	92,199	87,249
Retained Earnings [Member]
Balance at	184,764	152,237	175,932	144,347
Net income	10,540	9,841	22,486	20,441
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 (loss) gain on available-for-sale securities	0	0	0	0
Dividends common stock	(3,188)	(3,080)	(6,302)	(5,790)
Dividends paid to noncontrolling interest			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
Balance at	192,116	158,998	192,116	158,998
Accumulated Other Comprehensive Income (Loss) [Member]
Balance at	(25,902)	(9,497)	(29,820)	(13,736)
Net income	0	0	0	0
Currency translation adjustments	(6,786)	3,587	(3,442)	7,400
Defined retirement benefit plans	499	325	969	649
Current period change in fair value of derivatives	103	78	199	174
Unrealized (loss) gain on available-for-sale securities	(5)	0	3	6
Dividends common stock	0	0	0	0
Dividends paid to noncontrolling interest			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
Balance at	(32,091)	(5,507)	(32,091)	(5,507)
Noncontrolling Interest [Member]
Balance at	8,015	7,359	6,977	6,721
Net income	630	714	1,377	1,344
Currency translation adjustments	(425)	69	(134)	77
Defined retirement benefit plans	0	0	0	0
Current period change in fair value of derivatives	0	0	0	0
Unrealized (loss) gain on available-for-sale securities	0	0	0	0
Dividends common stock	0	0	0	0
Dividends paid to noncontrolling interest	(30)		(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
Balance at	$ 8,190	$ 8,142	$ 8,190	$ 8,142