Equity and Noncontrolling Interest (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Beginning Balance	$ 422,763	$ 421,975	$ 408,864	$ 412,606
Net Income	19,370	12,341	32,157	19,955
Amounts reported in other comprehensive income (loss)	(15,784)	9,074	(9,327)	15,040
Dividends, Common Stock	(4,933)	(4,724)	(9,662)	(9,311)
Distributions to Noncontrolling Affiliate Shareholders			(834)
Share Issuance and Equity-Based Compensation Plans	1,261	928	1,479	1,304
Ending Balance	422,677	439,594	422,677	439,594
Common Stock [Member]
Beginning Balance	13,323	13,291	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
Share Issuance and Equity-Based Compensation Plans	8	19	23	32
Ending Balance	13,331	13,310	13,331	13,310
Additional Paid-in Capital [Member]
Beginning Balance	93,731	112,838	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
Share Issuance and Equity-Based Compensation Plans	1,253	909	1,456	1,272
Ending Balance	94,984	113,747	94,984	113,747
Retained Earnings [Member]
Beginning Balance	373,185	366,819	365,182	364,414
Net Income	19,246	11,906	31,978	18,898
Amounts reported in other comprehensive income (loss)	0	0	0	0
Dividends, Common Stock	(4,933)	(4,724)	(9,662)	(9,311)
Distributions to Noncontrolling Affiliate Shareholders			0
Share Issuance and Equity-Based Compensation Plans	0	0	0	0
Ending Balance	387,498	374,001	387,498	374,001
Accumulated Other Comprehensive Income (Loss) [Member]
Beginning Balance	(58,738)	(81,961)	(65,100)	(87,407)
Net Income	0	0	0	0
Amounts reported in other comprehensive income (loss)	(15,613)	9,023	(9,251)	14,469
Dividends, Common Stock	0	0	0	0
Distributions to Noncontrolling Affiliate Shareholders			0
Share Issuance and Equity-Based Compensation Plans	0	0	0	0
Ending Balance	(74,351)	(72,938)	(74,351)	(72,938)
Noncontrolling Interest [Member]
Beginning Balance	1,262	10,988	1,946	9,846
Net Income	124	435	179	1,057
Amounts reported in other comprehensive income (loss)	(171)	51	(76)	571
Dividends, Common Stock	0	0	0	0
Distributions to Noncontrolling Affiliate Shareholders			(834)
Share Issuance and Equity-Based Compensation Plans	0	0	0	0
Ending Balance	$ 1,215	$ 11,474	$ 1,215	$ 11,474