Consolidated Statements of Changes in Shareholders’ Equity - USD ($) $ in Thousands	Total	Common Stock	Retained Earnings	Accumulated Other Comprehensive Loss	Noncontrolling Interests
Balance at Dec. 31, 2014	$ 681,981	$ 317,199	$ 513,672	$ (152,193)	$ 3,303
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Net Income	91,332		91,068		264
Other comprehensive (loss) income	(38,782)			(38,242)	(540)
Stock issued	16,124	15,723			401
Stock purchased	(14,474)	(14,365)			(109)
Dividends declared	(48,035)	7,925	(55,960)
Balance at Dec. 31, 2015	688,146	326,482	548,780	(190,435)	3,319
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Net Income	93,313		93,079		234
Other comprehensive (loss) income	(6,020)			(6,165)	145
Stock issued	17,007	17,007
Stock purchased	(11,632)	(11,272)			(360)
Dividends declared	(49,925)	16,554	(66,479)
Balance at Dec. 31, 2016	730,889	348,771	575,380	(196,600)	3,338
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Adoption of ASU 2018-02				0
Net Income	71,935		71,608		327
Other comprehensive (loss) income	(9,835)			(10,039)	204
Stock issued	18,016	17,389			627
Stock purchased	(14,084)	(13,687)			(397)
Dividends declared	(35,373)	35,214	(70,587)
Balance at Dec. 31, 2017	761,548	$ 387,687	619,916	(250,154)	$ 4,099
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Adoption of ASU 2018-02	$ 0		$ 43,515	$ (43,515)