Equity and Noncontrolling Interest (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Jan. 01, 2019	Jan. 01, 2018
Beginning Balance	$ 446,363	$ 422,763	$ 436,369	$ 409,618
Cumulative effect of accounting change					$ (44)	$ (754)
Adjusted Beginning Balance					436,325	408,864
Net income	15,649	19,370	29,549	32,157
Amounts reported in other comprehensive income (loss)	310	(15,784)	1,857	(9,327)
Dividends, Common Stock	(5,135)	(4,933)	(10,068)	(9,662)
Distributions to Noncontrolling Affiliate Shareholders				(834)
Share issuance and equity-based compensation plans	774	1,261	298	1,479
Ending Balance	457,961	422,677	457,961	422,677
Common Stock [Member]
Beginning Balance	13,334	13,323	13,338	13,308
Cumulative effect of accounting change					0	0
Adjusted Beginning Balance					13,338	13,308
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	4	8	0	23
Ending Balance	13,338	13,331	13,338	13,331
Additional Paid-in Capital [Member]
Beginning Balance	96,832	93,731	97,304	93,528
Cumulative effect of accounting change					0	0
Adjusted Beginning Balance					97,304	93,528
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	770	1,253	298	1,456
Ending Balance	97,602	94,984	97,602	94,984
Retained Earnings [Member]
Beginning Balance	413,992	373,185	405,125	365,936
Cumulative effect of accounting change					(44)	(754)
Adjusted Beginning Balance					405,081	365,182
Net income	15,591	19,246	29,435	31,978
Amounts reported in other comprehensive income (loss)	0	0	0	0
Dividends, Common Stock	(5,135)	(4,933)	(10,068)	(9,662)
Distributions to Noncontrolling Affiliate Shareholders				0
Share issuance and equity-based compensation plans	0	0	0	0
Ending Balance	424,448	387,498	424,448	387,498
Accumulated Other Comprehensive Income (Loss) [Member]
Beginning Balance	(79,167)	(58,738)	(80,715)	(65,100)
Cumulative effect of accounting change					0	0
Adjusted Beginning Balance					(80,715)	(65,100)
Net income	0	0	0	0
Amounts reported in other comprehensive income (loss)	286	(15,613)	1,834	(9,251)
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	(78,881)	(74,351)	(78,881)	(74,351)
Noncontrolling Interest [Member]
Beginning Balance	1,372	1,262	1,317	1,946
Cumulative effect of accounting change					0	0
Adjusted Beginning Balance					$ 1,317	$ 1,946
Net income	58	124	114	179
Amounts reported in other comprehensive income (loss)	24	(171)	23	(76)
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	$ 1,454	$ 1,215	$ 1,454	$ 1,215