Equity and Noncontrolling Interest (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Beginning Balance	$ 439,594	$ 400,233	$ 412,606	$ 381,243
Net Income	11,704	16,351	31,659	45,100
Amounts reported in other comprehensive income (loss)	6,112	(60)	21,152	1,375
Repurchases of common stock	0	0	0	(5,859)
Dividends, Common Stock	(4,722)	(4,575)	(14,033)	(13,374)
Acquisition of Noncontrolling Interest		40		40
Share Issuance and Equity-Based Compensation Plans	(629)	1,678	675	5,006
Excess Tax Benefit From Stock Option Exercises	0	31	0	167
Ending Balance	452,059	413,698	452,059	413,698
Common Stock [Member]
Beginning Balance	13,310	13,250	13,278	13,288
Net Income	0	0	0	0
Amounts reported in other comprehensive income (loss)	0	0	0	0
Repurchases of common stock	0	0	0	(84)
Dividends, Common Stock	0	0	0	0
Share Issuance and Equity-Based Compensation Plans	(11)	7	21	53
Excess Tax Benefit From Stock Option Exercises	0	0	0	0
Ending Balance	13,299	13,257	13,299	13,257
Additional Paid-in Capital [Member]
Beginning Balance	113,747	109,751	112,475	106,333
Net Income	0	0	0	0
Amounts reported in other comprehensive income (loss)	0	0	0	0
Repurchases of common stock	0	0	0	0
Dividends, Common Stock	0	0	0	0
Share Issuance and Equity-Based Compensation Plans	(618)	1,671	654	4,953
Excess Tax Benefit From Stock Option Exercises	0	31	0	167
Ending Balance	113,129	111,453	113,129	111,453
Retained Earnings [Member]
Beginning Balance	374,001	340,127	364,414	326,740
Net Income	11,142	16,008	30,040	43,969
Amounts reported in other comprehensive income (loss)	0	0	0	0
Repurchases of common stock	0	0	0	(5,775)
Dividends, Common Stock	(4,722)	(4,575)	(14,033)	(13,374)
Share Issuance and Equity-Based Compensation Plans	0	0	0	0
Excess Tax Benefit From Stock Option Exercises	0	0	0	0
Ending Balance	380,421	351,560	380,421	351,560
Accumulated Other Comprehensive Income (Loss) [Member]
Beginning Balance	(72,938)	(71,790)	(87,407)	(73,316)
Net Income	0	0	0	0
Amounts reported in other comprehensive income (loss)	6,265	(237)	20,734	1,289
Repurchases of common stock	0	0	0	0
Dividends, Common Stock	0	0	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	(66,673)	(72,027)	(66,673)	(72,027)
Noncontrolling Interest [Member]
Beginning Balance	11,474	8,895	9,846	8,198
Net Income	562	343	1,619	1,131
Amounts reported in other comprehensive income (loss)	(153)	177	418	86
Repurchases of common stock	0	0	0	0
Dividends, Common Stock	0	0	0	0
Acquisition of Noncontrolling Interest		40		40
Share Issuance and Equity-Based Compensation Plans	0	0	0	0
Excess Tax Benefit From Stock Option Exercises	0	0	0	0
Ending Balance	$ 11,883	$ 9,455	$ 11,883	$ 9,455