Equity and Noncontrolling Interest (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Beginning Balance	$ 422,677	$ 439,594	$ 408,864	$ 412,606
Net Income	19,771	11,704	51,928	31,659
Amounts reported in other comprehensive income (loss)	(6,019)	6,112	(15,346)	21,152
Dividends, Common Stock	(4,933)	(4,722)	(14,595)	(14,033)
Distributions to Noncontrolling Affiliate Shareholders	0	0	(834)	0
Share Issuance and Equity-Based Compensation Plans	1,140	(629)	2,619	675
Ending Balance	432,636	452,059	432,636	452,059
Common Stock [Member]
Beginning Balance	13,331	13,310	13,308	13,278
Net Income	0	0	0	0
Amounts reported in other comprehensive income (loss)	0	0	0	0
Dividends, Common Stock	0	0	0	0
Distributions to Noncontrolling Affiliate Shareholders	0	0	0	0
Share Issuance and Equity-Based Compensation Plans	3	(11)	26	21
Ending Balance	13,334	13,299	13,334	13,299
Additional Paid-in Capital [Member]
Beginning Balance	94,984	113,747	93,528	112,475
Net Income	0	0	0	0
Amounts reported in other comprehensive income (loss)	0	0	0	0
Dividends, Common Stock	0	0	0	0
Distributions to Noncontrolling Affiliate Shareholders	0	0	0	0
Share Issuance and Equity-Based Compensation Plans	1,137	(618)	2,593	654
Ending Balance	96,121	113,129	96,121	113,129
Retained Earnings [Member]
Beginning Balance	387,498	374,001	365,182	364,414
Net Income	19,690	11,142	51,668	30,040
Amounts reported in other comprehensive income (loss)	0	0	0	0
Dividends, Common Stock	(4,933)	(4,722)	(14,595)	(14,033)
Distributions to Noncontrolling Affiliate Shareholders	0	0	0	0
Share Issuance and Equity-Based Compensation Plans	0	0	0	0
Ending Balance	402,255	380,421	402,255	380,421
Accumulated Other Comprehensive Income (Loss) [Member]
Beginning Balance	(74,351)	(72,938)	(65,100)	(87,407)
Net Income	0	0	0	0
Amounts reported in other comprehensive income (loss)	(5,981)	6,265	(15,232)	20,734
Dividends, Common Stock	0	0	0	0
Distributions to Noncontrolling Affiliate Shareholders	0	0	0	0
Share Issuance and Equity-Based Compensation Plans	0	0	0	0
Ending Balance	(80,332)	(66,673)	(80,332)	(66,673)
Noncontrolling Interest [Member]
Beginning Balance	1,215	11,474	1,946	9,846
Net Income	81	562	260	1,619
Amounts reported in other comprehensive income (loss)	(38)	(153)	(114)	418
Dividends, Common Stock	0	0	0	0
Distributions to Noncontrolling Affiliate Shareholders	0	0	(834)	0
Share Issuance and Equity-Based Compensation Plans	0	0	0	0
Ending Balance	$ 1,258	$ 11,883	$ 1,258	$ 11,883