Condensed Consolidated Statements of Changes in Shareholders’ Equity (USD $) In Thousands, unless otherwise specified	Total	Common Stock	Common Stock Subscribed, Unissued	Retained Earnings	Accumulated Other Comprehensive Loss	Noncontrolling Interests
Balance at Dec. 31, 2011	$ 571,394	$ 257,630	$ 0	$ 458,139	$ (150,364)	$ 5,989
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Net income	16,429			16,355		74
Other comprehensive income	5,037				5,195	(158)
Stock issued	5,250	5,250
Stock purchased	(4,304)	(1,542)				(2,762)
Advance payments	369		369
Dividends declared	(3,921)			(3,921)
Balance at Mar. 31, 2012	590,254	261,338	369	470,573	(145,169)	3,143
Balance at Dec. 31, 2011						5,989
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Stock issued
Balance at Sep. 30, 2012
Balance at Dec. 31, 2012	600,216	310,008	0	453,770	(166,814)	3,252
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Net income	7,979			7,946		33
Other comprehensive income	2,437				2,505	(68)
Stock issued	5,843	5,843
Stock purchased	(3,017)	(2,954)				(63)
Advance payments	405		405
Dividends declared	(4,700)			(4,700)
Balance at Mar. 31, 2013	$ 609,163	$ 312,897	$ 405	$ 457,016	$ (164,309)	$ 3,154