Condensed Consolidated Statements of Changes in Shareholders’ Equity - USD ($) $ in Thousands	Total	Common Stock	Common Stock Subscribed, Unissued	Retained Earnings	Accumulated Other Comprehensive Loss	Noncontrolling Interests
Balance at Dec. 31, 2014	$ 681,981	$ 317,199	$ 0	$ 513,672	$ (152,193)	$ 3,303
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	12,494			12,460		34
Other comprehensive income (loss)	(3,461)				(3,238)	$ (223)
Stock issued	7,365	7,365
Stock purchased	(3,748)	(3,658)				$ (90)
Advance payments	468		468
Dividends declared	(4,815)			(4,815)
Balance at Mar. 31, 2015	690,284	320,906	468	521,317	(155,431)	3,024
Balance at Dec. 31, 2015	688,146	326,482	0	548,780	(190,435)	3,319
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	15,097			15,045		52
Other comprehensive income (loss)	7,976				7,735	$ 241
Stock issued	8,015	8,015
Stock purchased	(2,888)	(2,647)				$ (241)
Advance payments	508		508
Dividends declared	(4,983)			(4,983)
Balance at Mar. 31, 2016	$ 711,871	$ 331,850	$ 508	$ 558,842	$ (182,700)	$ 3,371