Interim Condensed Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	AOCI Attributable to Parent [Member]	Total
Balance, shares (in shares) at Dec. 31, 2014	10,836,659	14,110,859
Balance at Dec. 31, 2014	$ 170,494	$ 140	$ 154,965	$ 343,941	$ 64,608	$ 734,148
Net income				25,600		25,600
Other comprehensive income (loss)					(9,493)	(9,493)
Stock–based compensation			1,132			1,132
Tax benefit (expense) from exercise of stock options			342			342
Shares sold – options exercised, shares (in shares)		123,001
Shares sold – options exercised		$ 2	5,741			5,743
Shares issued in conversion of preferred stock to common stock (in shares)	(63,947)	15,476
Shares issued in conversion of preferred stock to common stock	$ (1,015)		1,015
Dividends declared to preferred stockholders ($0.40 per share)				(4,335)		(4,335)
Dividends declared to common stockholders ($0.74 per share)				(10,534)		(10,534)
Balance, shares (in shares) at Jun. 30, 2015	10,772,712	14,249,336
Balance at Jun. 30, 2015	$ 169,479	$ 142	163,195	354,672	55,115	742,603
Other comprehensive income					(9,493)	(9,493)
Balance, shares (in shares) at Dec. 31, 2014	10,836,659	14,110,859
Balance at Dec. 31, 2014	$ 170,494	$ 140	154,965	343,941	64,608	$ 734,148
Shares sold – options exercised, shares (in shares)						389,498
Balance, shares (in shares) at Dec. 31, 2015		15,000,616
Balance at Dec. 31, 2015		$ 150	209,469	368,013	53,364	$ 630,996
Net income				25,565		25,565
Other comprehensive income (loss)					18,533	18,533
Stock–based compensation			494			494
Tax benefit (expense) from exercise of stock options			(1,134)			$ (1,134)
Shares sold – options exercised, shares (in shares)		278,623				480,275
Shares sold – options exercised		$ 3	10,067			$ 10,070
Dividends declared to preferred stockholders ($0.40 per share)
Dividends declared to common stockholders ($0.74 per share)				(12,981)		(12,981)
Balance, shares (in shares) at Jun. 30, 2016		15,279,239
Balance at Jun. 30, 2016		$ 153	$ 218,896	$ 380,597	71,897	671,543
Other comprehensive income					$ 18,533	$ 18,533